DESCRIPTION
CYCLIC SULFATE COMPOUND, NON-AQUEOUS ELECTROLYTE SOLUTION
CONTAINING SAME, AND LITHIUM SECONDARY BATTERY
Technical Field
[0001] The present invention relates to a non-aqueous electrolyte solution having an
excellent performance of maintaining the open circuit voltage during the storage of a battery
in a charged state, a lithium secondary battery using the electrolyte solution, an additive for
lithium secondary batteries which is useful as an additive for electrolyte solutions, and a
cyclic sulfate compound suitable for the additive.
Background Art
[0002] In recent years, lithium secondary batteries are widely used as power sources for
electronic devices such as mobile telephones and notebook computers, or for electric cars or
electric power storage. Particularly recently, there is a rapidly increasing demand for a high
capacity and high power battery with a high energy density, which can be mounted in hybrid
cars or electric cars.
Lithium secondary batteries are primarily composed of a positive electrode and a
negative electrode, which contain materials capable of absorption and desorption of lithium,
and a non-aqueous electrolyte solution containing a lithium salt and a non-aqueous solvent.
Examples of positive electrode active materials used in a positive electrode include
lithium metal oxides such as LiCo02, LiMn02, LiNi02, and LiFeP04.
Furthermore, as the non-aqueous electrolyte solution, solutions prepared by mixing a
mixed solvent (non-aqueous solvent) of carbonates such as ethylene carbonate, propylene
carbonate, ethylene carbonate or methyl carbonate, with a Li electrolyte such as LiPF6, LiBF4,
LiN(S02CF3)2 or LiN(S02CF2CF3)2a, re used.
On the other hand, as the active material for a negative electrode that is used in
negative electrodes, metal lithium, metal compounds (elemental metals, oxides, alloys with
lithium, and the like) capable of absorption and desorption of lithium, and carbon materials
are known. Particularly, lithium secondary batteries employing cokes, artificial graphite or
natural graphite, which are all capable of absorption and desorption of lithium, have been put
to practical use.
[0003] Among the battery performances, particularly in relation to lithium secondary
batteries for automotive applications, an increase in output power and an increase in service
life are required. It has been a considerable challenge to achieve a balance between a
reduction of the resistance of a battery under various conditions and an enhancement of the
service life performance of a battery.
One of the factors known to cause an increase in the resistance of a battery is a
passivation film based on a solvent decomposition product or an inorganic salt, which is
formed on the surface of a negative electrode. In general, it is known that since lithium
metal is present among the negative electrode active material under the charging conditions, a
reductive decomposition reaction of the electrolyte solution occurs at the surface of the
negative electrode. In a case in which such reductive decomposition continuously occurs,
the resistance of the battery increases, the charge-discharge efficiency decreases, and the
energy density of the battery decreases. Furthermore, on the other hand, it is also known in
regard to the positive electrode that a deterioration reaction occurs over time, the resistance
continually increases, and a decrease in the battery performance is caused. In order to
overcome these problems, attempts have been made to add various compounds to electrolyte
solution.
As a trial for the purpose, it has been attempted to improve the battery performance
by incorporating various cyclic sulfate compounds (see, for example, Japanese Patent
Application Laid-Open (JP-A) No. 10-1 89042, JP-A No. 2003-1 5 1623, JP-A No.
2003-308875, JP-A NO. 2004-22523, and JP-A NO. 2005-01 1762).
SUMMARY OF INVENTION
Technical Problem
[0004] It is believed that by adding the cyclic sulfates having lower alkyl groups, which are
described in the various documents mentioned above, dense passivation films are formed on
negative electrodes, and as the reaction between the organic solvent in the electrolyte solution
and the negative electrode is continuously suppressed by these passivation films, retention of
the battery capacity is brought about.
However, it has been found that when those cyclic sulfates having lower alkyl groups
as described in the various documents mentioned above are added, there occurs a new
problem that the potential in a charged state is lowered (more particularly, the open circuit
voltage decreases during the storage of a battery in a charged state).
[0005] The invention was achieved in order to cope with the problem described above, and it
is an object of the invention to provide a non-aqueous electrolyte solution which can
significantly suppress a decrease in the open circuit voltage during the storage of a battery in a
charged state, while improving the capacity retention performance of the battery, and a
lithium secondary battery using the non-aqueous electrolyte solution.
It is another object of the invention to provide an additive for lithium secondary
batteries which is useful for such a non-aqueous electrolyte solution, and a cyclic sulfate
compound which is useful as an additive for non-aqueous electrolyte solutions.
Solution to Problem
[0006] The inventors of the invention have conducted a thorough investigation in connection
with the problems described above, and as a result, the inventors found that when a particular
compound is added to a non-aqueous electrolyte solution for lithium secondary batteries, a
decrease in potential (a decrease in the open circuit voltage during the storage of a battery in a
charged state) can be markedly suppressed, while the capacity retention performance is
improved. Thus, the inventors completed the invention.
That is, the means for solving the problems of the invention are as follows.
[0007] <1> A non-aqueous electrolyte solution, comprising:
a cyclic sulfate compound represented by the following formula (I).
[OOOS]
0
[0009] In formula (I), R' represents a group represented by the above formula (11) or a group
represented by the above formula (111); and R2 represents a hydrogen atom, an alkyl group
having from 1 to 6 carbon atoms, a group represented by formula (11), or a group represented
by formula (111).
In formula (11), R3 represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
3
C
wavy line in formula (II), formula (111) and formula (IV) represents the position of bonding.
In a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
[0010] <2> The non-aqueous electrolyte solution described in item , wherein in formula
(I), R' represents a group represented by formula (11) (provided that in formula (11), R3
represents a fluorine atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated
alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon
atoms, or a group represented by formula (IV)), or a group represented by formula (111); and
R2 represents a hydrogen atom, an alkyl group having from 1 to 3 carbon atoms, a group
represented by formula (11) (provided that in formula (11), R3 represents a fluorine atom, an
alkyl group having from 1 to 3 carbon atoms, a halogenated alkyl group having from 1 to 3
carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, or a group represented by
formula (IV)), or a group represented by formula (111).
<3> The non-aqueous electrolyte solution described in item or <2>, wherein in
formula (I), R' represents a group represented by formula (11) (provided that in formula (11),
R3 represents a fluorine atom, a methyl group, an ethyl group, a methoxy group, an ethoxy
group, or a group represented by formula (IV)), or a group represented by formula (111); and
R2 represents a hydrogen atom or a methyl group.
<4> The non-aqueous electrolyte solution described in any one of items <1> to <3>,
wherein in formula (I), R' represents a group represented by formula (111), and R~ represents a
hydrogen atom.
[0011] <5> The non-aqueous electrolyte solution described in any one of items <1> to <4>,
further comprising at least one of an electrolyte compound represented by the following
formula (V) or lithium difluorophosphate.
[OO 1 21
[0013] In formula (V), M represents an alkali metal; Y represents a transition element, or an
element of Group 13, Group 14 or Group 15 of the Periodic Table of Elements; b represents
an integer from 1 to 3; m represents an integer from 1 to 4; n represents an integer from 0 to 8;
q represents 0 or 1 ; R" represents an alkylene group having from 1 to 10 carbon atoms, a
halogenated alkylene group having from 1 to 10 carbon atoms, an arylene group having from
6 to 20 carbon atoms, or a halogenated arylene group having from 6 to 20 carbon atoms,
wherein such groups may each contain a substituent or a heteroatom in the structure, and
when q is 1 and m is 2 to 4, m units of R" may be bonded to each other; R12 represents a
halogen atom, an alkyl group having from 1 to 10 carbon atoms, a halogenated alkyl group
having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon atoms, a
halogenated aryl group having from 6 to 20 carbon atoms, or -Q3R13, wherein such groups,
other than -Q3 R 13, may each contain a substituent or a heteroatom in the structure, and when n
represents an integer from 2 to 8, n units of R12 may be bonded to each other to form a ring;
Q1, Q2, and Q3 each independently represent 0, S or NR"; and R" and R14 each
independently represent a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, a
halogenated alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20
carbon atoms, or a halogenated aryl group having from 6 to 20 carbon atoms, wherein such
groups may each contain a substituent or a heteroatom in the structure, and when plural RI3's
or plural RI4's are present, the respective groups may be bonded to each other to form a ring.
[0014] <6> The non-aqueous electrolyte solution described in item <5>, wherein the
electrolyte compound represented by formula (V) is at least one compound selected from the
group consisting of a compound represented by the following formula (VI), a compound
represented by the following formula (VII), a compound represented by the following formula
(VIII), and a compound represented by the following formula (IX).
[00 1 51
[0016] In formulae (VI) to (IX), M has the same definition as M in formula (V).
[0017] <7> The non-aqueous electrolyte solution described in any one of items <1> to <6>,
further comprising a compound represented by the following formula (X).
[OO 181
[OO 191 In formula (X), Y' and y2 each independently represent a hydrogen atom, a methyl
group, an ethyl group, or a propyl group.
[0020] <8> The non-aqueous electrolyte solution described in any one of items <1> to <7>,
firther comprising a compound represented by the following formula (XI).
[002 11
[0022] In formula (XI), x', x2, x3 and x4 each independently represent an alkyl group,
having from 1 to 3 carbon atoms, that may be substituted with a fluorine atom; a hydrogen
atom; a fluorine atom; or a chlorine atom, provided that X' to x4 are not both hydrogen atoms
at the same time.
COO231 <9> The non-aqueous electrolyte solution described in any one of items <1> to <8>,
wherein the content of the cyclic sulfate compound represented by formula (I) is from 0.001
mass% to 10 mass%.
The non-aqueous electrolyte solution described in any one of items <5> to <9>,
wherein the content of at least one of the electrolyte compound represented by formula (V) or
the lithium difluorophosphate is fiom 0.001 mass% to 10 mass%.
<11> The non-aqueous electrolyte solution described in any one of items <7> to
, wherein the content of the compound represented by formula (X) is from 0.001 mass%
to 10 mass%.
<12> The non-aqueous electrolyte solution described in any one of items <8> to
<1 I>, wherein the content of the compound represented by formula (XI) is from 0.001 mass%
7
to 10 mass%.
[0024] <13> An additive for a lithium secondary battery, the additive comprising a cyclic
sulfate compound represented by the following formula (I) as an active ingredient.
[0025]
0
[0026] In formula (I), R' represents a group represented by the above formula (11) or a group
represented by the above formula (111); and R2 represents a hydrogen atom, an alkyl group
having from 1 to 6 carbon atoms, a group represented by formula (11), or a group represented
by formula (111).
In formula (11), R3 represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding.
In a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
[0027] <14> A cyclic sulfate compound represented by the following formula (I).
[0028]
[0029] In formula (I), R' represents a group represented by the above formula (11) or a group
represented by the above formula (111); and R2 represents a hydrogen atom, an alkyl group
having from 1 to 6 carbon atoms, a group represented by formula (11), or a group represented
by formula (111).
In formula (11), R3 represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding.
In a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
[0030] <15> The cyclic sulfate compound described in item <14>, which is represented by
the following formula (XII).
[003 11
[0032] In formula (XII), R2 represents a hydrogen atom or an alkyl group having from 1 to 6
carbon atoms; and R3 represents a halogen atom, an alkyl group having from 1 to 6 carbon
atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group having
from 1 to 6 carbon atoms, or a group represented by formula (IV).
[0033] <16> The cyclic sulfate compound described in item <15>, wherein in formula (XII),
R2 represents a hydrogen atom or a methyl group; and R3 represents a fluorine atom, a methyl
group, an ethyl group, a methoxy group, an ethoxy group, or a group represented by formula
[0034] <17> The cyclic sulfate compound described in item , which is
4-methylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
4-ethylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane, or
bis((2,2-dioxo- 1,3,2-dioxathiolane-4-y1)methyl)s ulfate.
[0035] <18> A lithium secondary battery, comprising:
a positive electrode;
a negative electrode including, as a negative electrode active material, at least one
selected from metal lithium, a lithium-containing alloy, a metal or alloy capable of alloying
with lithium, an oxide capable of doping and dedoping of lithium ions, transition metal
nitrides capable of doping and dedoping of lithium ions, or a carbon material capable of
doping and dedoping of lithium ions; and
the non-aqueous electrolyte solution described in any one of items <1> to <12>.
a [0036] 49, A lithium secondary battery obtained by charging or discharging a lithium
secondary battery that includes: a positive electrode; a negative electrode containing, as a
negative electrode active material, at least one selected from metal lithium, a
lithium-containing alloy, a metal or alloy capable of alloying with lithium, an oxide capable of
doping and dedoping of lithium ions, transition metal nitrides capable of doping and dedoping
of lithium ions, or a carbon material capable of doping and dedoping of lithium ions; and the
non-aqueous electrolyte solution described in any one of items to <12>.
Advantageous Effects of Invention
[0037] According to the invention, a non-aqueous electrolyte solution which is used in
lithium secondary batteries, and can markedly suppress a decrease in the open circuit voltage
during the storage of a battery in a charged state, while improving the capacity retention
performance of the battery, and a lithium secondary battery using the non-aqueous electrolyte
solution can be provided.
Furthermore, according to the invention, an additive for lithium secondary batteries
which is useful for such a non-aqueous electrolyte solution, and a novel cyclic sulfate
compound which is useful as an additive for non-aqueous electrolyte solutions can be
provided.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1 is a schematic cross-sectional diagram of a coin cell illustrating an example of
the lithium secondary battery of the invention.
DESCRIPTION OF EMBODIMENTS
[0039] The cyclic sulfate compound of the invention, a non-aqueous electrolyte solution
using the compound, an additive for lithium secondary batteries, and a lithium secondary
battery will be described specifically.
[0040] [Cyclic sulfate compound represented by formula (I)]
The cyclic sulfate compound of the invention is a cyclic sulfate compound
represented by the following formula (I).
[004 1 ]
[0042] In formula (I), R' represents a group represented by the above formula (11) or a group
represented by the above formula (111); and R2 represents a hydrogen atom, an alkyl group
having from 1 to 6 carbon atoms, a group represented by formula (11), or a group represented
by formula (111).
In formula (11), R3 represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding.
In a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
[0043] In formula (I), specific examples of the "halogen atom" include a fluorine atom, a
chlorine atom, a bromine atom, and an iodine atom.
The halogen atom is preferably a fluorine atom.
[0044] In formula (I), the "alkyl group having from 1 to 6 carbon atoms" is a linear or
branched alkyl group having from 1 to 6 carbon atoms, and specific examples thereof include
a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl
group, a sec-butyl group, a tert-butyl group, a pentyl group, a 2-methylbutyl group, a
1 -methylpentyl group, a neopentyl group, a 1 -ethylpropyl group, a hexyl group, and a
3,3 -dimethylbutyl group.
The alkyl group having from 1 to 6 carbon atoms is more preferably an alkyl group
having from 1 to 3 carbon atoms.
[0045] In formula (I), the "halogenated alkyl group having from 1 to 6 carbon atoms" is a
12
linear or branched halogenated alkyl group having from 1 to 6 carbon atoms, and specific
examples thereof include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl
group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, a perfluoropropyl group, a
perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroisopropyl
group, a perfluoroisobutyl group, a chloromethyl group, a chloroethyl group, a chloropropyl
group, a bromomethyl group, a bromoethyl group, a bromopropyl group, an iodomethyl group,
an iodoethyl group, and an iodopropyl group.
The halogenated alkyl group having from 1 to 6 carbon atoms is more preferably a
halogenated alkyl group having from 1 to 3 carbon atoms.
[0046] In formula (I), the "alkoxy group having from 1 to 6 carbon atoms" is a linear or
branched alkoxy group having from 1 to 6 carbon atoms, and specific examples thereof
include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy
group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a
2-methylbutoxy group, a 1-methylpentyloxy group, a neopentyloxy group, a 1 -ethylpropoxy
group, a hexyloxy group, and a 3,3-dimethylbutoxy group.
The alkoxy group having from 1 to 6 carbon atoms is more preferably an alkoxy
group having from 1 to 3 carbon atoms.
[0047] R' in formula (I) is preferably a group represented by formula (11) (in formula (11), R3
is preferably a fluorine atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated
alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon
atoms, or a group represented by formula (IV)), or a group represented by formula (111).
R2 in formula (I) is preferably a hydrogen atom, an alkyl group having from 1 to 3
carbon atoms, a group represented by formula (11) (in formula (11), R3 is preferably a fluorine
atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated alkyl group having fiom
1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, or a group represented
by formula (IV)), or a group represented by formula (111), and more preferably a hydrogen
atom or a methyl group. R2 is particularly preferably a hydrogen atom.
[0048] In a case in which R' in formula (I) is a group represented by formula (11), R3 in
formula (11) is a halogen atom, an alkyl group having fiom 1 to 6 carbon atoms, a halogenated
alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon
atoms or a group represented by formula (IV) as described above, but R3 is more preferably a
fluorine atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated alkyl group
having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, or a
group represented by formula (IV), and even more preferably a fluorine atom, a methyl group,
13
b an ethyl group, a methoxy group, an ethoxy group, or a group represented by formula (IV).
In a case in which R2 in formula (I) is a group represented by formula (II), R3 in
formula (11) has the same preferable definition as R3 in the case where R' in formula (I) is a
group represented by formula (11).
[0049] A preferred combination of R' and R2 in formula (1) is a combination in which R'
represents a group represented by formula (11) (in formula (11), R3 is preferably a fluorine
atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated alkyl group having from
1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, or a group represented
by formula (IV)), or a group represented by formula (III), and R2 represents a hydrogen atom,
an alkyl group having from 1 to 3 carbon atoms, a group represented by formula (11) (in
formula (11), R3 is preferably a fluorine atom, an alkyl group having from 1 to 3 carbon atoms,
a halogenated alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to
3 carbon atoms, or a group represented by formula (IV)), or a group represented by formula
(111).
A more preferred combination of R' and R2 in formula (I) is a combination in which
R' represents a group represented by formula (11) (in formula (11), R3 is preferably a fluorine
atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, or a group
represented by formula (IV)), or a group represented by formula (111), and R2 represents a
hydrogen atom or a methyl group.
A particularly preferred combination of R' and R2 in formula (I) is a combination in
which in formula (I), R' represents a group represented by formula (111) and R2 represents a
hydrogen atom (most preferably 1,2:3,4-di-0-sulfanyl-meso-erythritol).
[0050] A cyclic sulfate compound in which R' in formula (I) is a group represented by
formula (TI), is a cyclic sulfate compound represented by the following formula (XII).
[005 11
[0052] In formula (XII), R2 and R3 have the same definitions as R~ and R3 in formula (I) and
14
formula (11), respectively.
[0053] The cyclic sulfate compound represented by formula (XII) is preferably a compound
in which R2 represents a hydrogen atom or an alkyl group having from 1 to 6 carbon atoms,
R3 represents a halogen atom, an alkyl group having from 1 to 6 carbon atoms, a halogenated
alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon
atoms, or a group represented by formula (IV).
Furthermore, the cyclic sulfate compound represented by formula (XII) is
particularly preferably a compound in which R* represents a hydrogen atom or a methyl group,
and R~ represents a fluorine atom, a methyl group, an ethyl group, a methoxy group, an
ethoxy group, or a group represented by formula (IV).
[0054] The cyclic sulfate compound represented by formula (I) is preferably
4-methylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
4-ethylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
bis((2,2-dioxo- 1,3,2-dioxathiolane-4-y1)methyl) sulfate, 1,2:3,4-di-0-sulfanyl-meso-erythritol,
or 1,2:3,4-di-0-sulfanyl-D,L-threitmolo;r e preferably
4-methylsulfonyloxymethyl-2,2-dioxo1-,3 ,2-dioxathiolane,
4-ethylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
bis((2,2-dioxo-1 ,3,2-dioxathiolane-4-y1)methyl)s ulfate, or
1,2:3,4-di-0-sulfanyl-meso-erythritola;n d particularly preferably
4-methylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
4-ethylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane, or
bis((2,2-dioxo-1 ,3,2-dioxathiolane-4-y1)methyl)s ulfate.
[0055] Specific examples of the cyclic sulfate compound represented by formula (I)
according to the invention [exemplary compound 1 to exemplary compound 301 will be
described in the following table by specifying the respective substituents for formula (I), but
the invention is not intended to be limited to these compounds.
In the structures of the exemplary compounds described below, "Me" represents a
methyl group, "Et" represents an ethyl group, "Pr" represents a propyl group, "iPr" represents
an isopropyl group, "Bu" represents a butyl group, "tBu" represents a tertiary butyl group,
"Pent'l represents a pentyl group, "Hex" represents a hexyl group, "OMe" represents a
methoxy group, "OEt" represents an ethoxy group, "OPr" represents a propoxy group, "OBu"
represents a butoxy group, "OPent" represents a pentyloxy group, "OHex" represents a
hexyloxy group. Furthermore, the "wavy line" in R' to R3 represents the position of
bonding.
15
Meanwhile, a 2,2-dioxo-1,3,2-dioxathiolaneri ng may have stereoisomers arising
from the substituents at the 4-position and the 5-position, but both the isomers are compounds
that are included in the invention.
[005 61
R~
Me
Et
P r
i Pr
Bu
tBu
Pent
Hex
CF3
C HF,
t?
H
H
H
H
H
H
Exemplary
Compound No.
1
2
3
4
5
6
R'
0
II
0
0
li
0
I1
0
0
II
0
0
II
0
0
I I
0
0
7
8
9
10
8
0
II
0
0
II
0
II
0
H
H
H
H
Exemplary
Compound No.
11
12
13
14
15
16
17
18
19
20
H
H
H
H
H
H
Me
Et
Hex
0
I I
0
R'
0
I l
0
0
II
0
0
II
0
0
It
0
0
II
0
0
II
0
0
it
0
II
0
0
il
0
0
I I
0
R3
cH2cF3
CbCbCF3
CH2C%CH2GF3
CH2CH,C&CH2CF3
CyCH2C&CH2CyCF3
0.
0
Me
Me
Me
Me
Exemplary
Compound No.
2 1
22
23
24
25
26
2 7
28
29
30
R'
0
ll
0
0.1
8S+ 0
Y+
' f ' o
0% I
S+ 8 0
0
II
0
0
II
0
0
II
0
0
I I
0
0
I I
0
I1
0
II
0
R2
0
II
0
H
0.1 8 s+ 0
H
H
H
H
H
H
H
R~
Et
-
-
F
OMe
OEt
0 Pr
OBu
0 Pent
OHex
[0059] Among the cyclic sulfate compounds represented by formula (I), in the case where
two or more asymmetric carbon atoms are present in the molecule, the relevant compounds
respectively have stereoisomers (diastereomers), but unless particularly stated otherwise, each
of the relevant compounds is a mixture of corresponding diastereomers.
For example, exemplary compound 22 (4,4'-bis(2,2-dioxo-1,3,2-dioxathiolaneh)a s
two kinds of diastereomers, which are indicated as exemplary compound 22a described below
and exemplary compound 22b described below, respectively.
In the present specification, the exemplary compound 22a may be referred to as
1,2:3,4-di-0-sulfanyl-meso-erythritola,n d the exemplary compound 22b may be referred to as
1,2:3,4-di-0-sulfanyl-D,L-threitol.
[0060]
Exemplan/ Compound 22a Exemplary Compound 22b
[0061] Meanwhile, the cyclic sulfate compound represented by formula (I) is useful as an
additive for lithium secondary batteries as will be described below.
COO621 The cyclic sulfate compound represented by formula (I) in the invention, in which R'
represents a group represented by formula (11) (for example, a cyclic sulfate compound
represented by formula (XII)), can be produced by, for example, the process that will be
described below, but the production method is not intended to be limited to this production
method.
100631
u - XSU2KU
(3) oxidizing agent - -
I I
step L step 3
[0064] In the above formula, R2 and R3 have the same definitions as R~ and R3 in formula (I),
respectively; and in the above formula, X represents a halogen atom.
[0065] (Step 1)
Step 1 is a step for producing a cyclic sulfurous acid ester represented by formula (2)
(hereinafter, also referred to as "compound (2)") by causing an alcohol derivative represented
by formula (I) (hereinafter, also referred to as "compound (1)") to react with thionyl chloride.
In regard to the present step, the solvent to be used is not particularly limited as long
as the solvent does not inhibit the reaction and is capable of dissolving the starting materials
to some extent, and examples thereof include ethers such as diethyl ether, dimethoxyethane,
tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, xylene and
chlorobenzene; aliphatic hydrocarbons such as hexane, cyclohexane and heptane; halogenated
hydrocarbons such as methylene chloride, 1,2-dichloroethane and chloroform; and mixture
thereof. Suitable solvents are halogenated hydrocarbons, aliphatic hydrocarbons, and
aromatic hydrocarbons, and more suitable solvents are methylene chloride and toluene.
The amount of thionyl chloride to be used is 1.0 rnol to 5.0 mol, and suitably 1.0 rnol
to 2.0, mol, relative to 1 rnol of the compound (1).
Regarding the amount of the solvent, usually 0.3 liters to 5 liters, and suitably 0.5
liters to 2 liters, can be used relative to 1 rnol of the compound (1).
The reaction temperature may vary depending on the raw material compounds,
reaction reagents, solvents and the like, but usually, the reaction can be carried out in a
temperature range of from -20°C to the reflux temperature in the reaction system, and suitably
-10°C to 20°C.
2 1
The reaction time may vary depending on the raw material compounds, reaction
reagents, solvents, reaction temperature, and the like, but usually, the reaction can be carried
out in the range of 0.5 hours to 48 hours, and suitably 0.5 hours to 24 hours.
The compound (1) used in the present step may be a commercially available product,
or is produced according to an already known method, for example, the method described in
Tetrahedron: Asymmetry, 2005, Vol. 16, p. 3268-3274.
[0066] (Step2)
Step 2 is a step for producing a cyclic sulfurous acid ester (4) represented by formula
(4) (hereinafter, also referred to as "compound (4)") by causing the cyclic sulfurous acid ester
represented by formula (2) (compound (2)) to react with a compound represented by formula
(3) in the presence of a base.
In the present step, the base to be used is not particularly limited as long as it is a
base exhibiting a deprotonation ability against the substrate, and examples thereof include
carbonates of alkali metals, such as sodium carbonate and potassium carbonate; hydrogen
carbonates of alkali metals, such as sodium hydrogen carbonate and potassium hydrogen
carbonate; organic bases such as triethylamine, N,N-dimethylaniline, and pyridine; metal
hydrides such as sodium hydride and potassium hydride; and metal alkoxides such as sodium
methoxide, sodium ethoxide, and potassium tert-butoxide. Suitable bases are organic bases,
and a more suitable base is triethylarnine.
In the present step, the solvent to be used is not particularly limited as long as the
solvent does not inhibit the reaction and is capable of dissolving the starting materials to some
extent, and examples thereof include ethers such as diethyl ether, dimethoxyethane,
tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, xylene, and
chlorobenzene; aliphatic hydrocarbons such as hexane, cyclohexane, and heptane;
halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, and chloroform;
esters such as ethyl acetate and butyl acetate; and mixture thereof. Suitable solvents include
halogenated hydrocarbons, aliphatic hydrocarbons, and aromatic hydrocarbons, and more
suitable solvents include methylene chloride and toluene.
The amount of the solvent that can be used is usually 0.5 liters to 10 liters, and
suitably 1.0 liter to 5 liters, relative to 1 mol of the compound (2).
The reaction temperature may vary depending on the raw material compounds,
reaction reagents, solvents and the like, but usually, the reaction can be carried out in a
temperature range of from -20°C to the reflux temperature in the reaction system, and suitably
-10°C to 50°C.
The reaction time may vary depending on the raw material compounds, reaction
reagents, solvents, reaction temperature, and the like, but usually, the reaction can be carried
out in the range of 0.5 hours to 48 hours, and suitably 0.5 hours to 24 hours.
[0067] (Step 3)
Step 3 is a step for producing a cyclic sulfate (XII) by causing the cyclic sulfurous
acid ester derivative represented by formula (4) (compound (4)) to react with an oxidizing
agent.
In the present step, examples of the oxidizing agent that may be used include
ruthenium salts such as ruthenium oxide, ruthenium chloride, and ruthenium bromide, or
hydrates thereof. Suitable oxidizing agents are ruthenium oxide and ruthenium trichloride
hydrate. Examples of co-oxidizing agents for the present reaction system include sodium
periodate, sodium perchlorate, sodium chlorite, and sodium hypochlorite, and suitable
examples include sodium hypochlorite and sodium periodate.
In the present step, the solvent to be used is not particularly limited as long as the
solvent does not inhibit the reaction and is capable of dissolving the starting materials to some
extent, and examples thereof include water; ethers such as diethyl ether, dimethoxyethane,
tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, xylene, and
chlorobenzene; aliphatic hydrocarbons such as hexane, cyclohexane, and heptane;
halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, and chloroform;
esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile and propionitrile;
and mixture thereof. Suitable solvents include esters, nitriles, water, and mixture thereof,
and a more suitable solvent is a mixture of acetonitrile and water.
The amount of the solvent that can be used is usually 0.5 liters to 10 liters, and
suitably 1.0 liter to 5 liters, relative to 1 mol of the compound (4).
The reaction temperature may vary depending on the raw material compounds,
reaction reagents, solvent and the like, but usually, the reaction can be carried out in a
temperature range of from -20°C to the reflux temperature in the reaction system, and suitably
-10°C to 50°C.
The reaction time may vary depending on the raw material compounds, reaction
reagents, solvent, reaction temperature, and the like, but usually, the reaction can be carried
out in the range of 0.5 hours to 48 hours, and suitably 0.5 hours to 24 hours.
[0068] The cyclic sulfate compound represented by formula (I) of the invention, in which R'
represents a group represented by formula (111), can be produced by an already known method,
for example, the method described in Tetrahedron Letters, 2000, vol. 41, p. 5053-5056.
[0069] The cyclic sulfate compound represented by formula (I) is useful as an additive for
lithium secondary batteries, particularly as an additive for a non-aqueous electrolyte solution
for lithium secondary batteries that will be described below. When this additive is added to a
non-aqueous electrolyte solution, a decrease in the open circuit voltage during the storage of a
battery in a charged state can be suppressed, while the capacity retention performance of the
battery is improved.
Now, a speculated reason why the cyclic sulfate compound represented by formula
(I) offers the above-described effects will be explained below.
As a result of the investigation conducted by the inventors of the invention, it was
found that when a compound having a structure of a simple cyclic sulfate, which is a cyclic
sulfate compound that is not included in formula (I), is used, the capacity retention
performance of a battery is improved, but a decrease in the potential (a decrease in the open
circuit voltage during the storage of the battery in a charged state) is brought about. In
contrast to this, it was found that when a cyclic sulfate compound represented by formula (I)
(a compound having a structure in which a sulfuric acid ester structure is further added to one
cyclic sulfate structure) is used, a decrease in potential can be suppressed while the capacity
retention performance of the battery is improved.
It is speculated that such an effect is obtained because at the time of forming a
passivation film on the negative electrode side by initial charging, as the cyclic sulfate
compound represented by formula (I) having the structure forms a passivation film more
firmly on the negative electrode side, continuous solvent decomposition or the like at the
electrode surface is suppressed.
However, the invention is not intended to be limited by the speculation as described
above.
[0070] The cyclic sulfate compound represented by formula (I) that is included in the
non-aqueous electrolyte solution of the invention may be used singly, or two or more kinds
may be used.
The content (if two or more kinds are included, the total content) of the cyclic sulfate
compound represented by formula (I) that is included in the non-aqueous electrolyte solution
of the invention is preferably 0.001 mass% to 10 mass%, and more preferably in the range of
0.05 mass% to 5 mass%, relative to the total mass of the non-aqueous electrolyte solution.
When the content is in this range, a decrease in the open circuit voltage during battery storage
can be more effectively suppressed, while the capacity of the battery is retained.
[0071] [Electrolyte compound represented by formula (V) and lithium difluorophosphate]
The non-aqueous electrolyte solution of the invention preferably hrther contains at
least one of an electrolyte compound represented by the following formula (V) or lithium
difluorophosphate (LiOP(0)F2), in addition to the cyclic sulfate compound represented by
formula (I) described above.
Thereby, a decrease in the open circuit voltage during the storage of a battery in a
charged state can be suppressed, while the capacity retention performance of the battery is
improved, and also, the low temperature discharge characteristics of the battery in the early
stage and during storage in a charged state can be enhanced. That is, when the non-aqueous
electrolyte solution of the invention contains the cyclic sulfate compound represented by
formula (I) described above, and at least one of an electrolyte compound represented by the
following formula (V) or lithium difluorophosphate (LiOP(0)F2), a good balance can be
achieved between the initial characteristics of a battery and the storage characteristics of the
battery.
Here, if the non-aqueous electrolyte solution does not contain the cyclic sulfate
compound represented by formula (I) described above but contains at least one of the
electrolyte compound represented by the following formula (V) or lithium difluorophosphate
(LiOP(0)F2), the effect of enhancing the low temperature discharge characteristics of the
battery in the early stage may be obtained, but the storage characteristics of the battery cannot
be sufficiently satisfied. That is, in this case, the low temperature discharge characteristics
during storage or the capacity retention performance during storage may deteriorate, and a
decrease in the open circuit voltage during storage may not be suppressed.
Hereinafter, the electrolyte compound represented by formula (V) will be described.
[0072]
[0073] In formula (V), M represents an alkali metal; Y represents a transition element, or an
element of Group 13, Group 14 or Group 15 of the Periodic Table of Elements; b represents
an integer from 1 to 3; m represents an integer fiom 1 to 4; n represents an integer from 0 to 8;
9 q represents 0 or 1 ; R" represents an alkylene group having from 1 to 10 carbon atoms, a
halogenated alkylene group having from 1 to 10 carbon atoms, an arylene group having from
6 to 20 carbon atoms, or a halogenated arylene group having from 6 to 20 carbon atoms,
wherein such groups may each contain a substituent or a heteroatom in the structure, and
when q is 1 and m is 2 to 4, m units of R" may be bonded to each other; RI2 represents a
halogen atom, an alkyl group having from 1 to 10 carbon atoms, a halogenated alkyl group
having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon atoms, a
halogenated aryl group having from 6 to 20 carbon atoms, or -Q3RI3, wherein such groups,
other than -Q3 R 13, may each contain a substituent or a heteroatom in the structure, and when n
represents an integer from 2 to 8, n units of RI2 may be bonded to each other to form a ring;
Q', Q*, and Q3 each independently represent 0, S or NR"; and R" and R" each
independently represent a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, a
halogenated alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20
carbon atoms, or a halogenated aryl group having from 6 to 20 carbon atoms, wherein such
groups may each contain a substituent or a heteroatom in the structure, and when plural R13's
or plural R14's are present, the respective groups may be bonded to each other to form a ring.
[0074] In the electrolyte compound represented by formula (V), M represents an alkali metal,
and Y represents a transition metal or an element of Group 13, Group 14 or Group 15 of the
Periodic Table of Elements. Among these, Y is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y,
Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf, or Sb, and more preferably Al, B or P. When Y represents
Al, B or P, synthesis of the anion compound is made relatively easy, and the production cost
can be lowered. Symbol b, which represents the valency of the anion and the number of
cations, is an integer from 1 to 3, and is preferably 1. If b is greater than 3, there is a
tendency that the salt of the anion compound does not easily dissolve in a mixed organic
solvent, which is not preferable. Furthermore, the constants m and n are values related to the
number of ligands and are determined in accordance with the kind of M; however, m
represents an integer from 1 to 4, and n represents an integer from 0 to 8. The constant q is 0
or 1. When q is 0, the chelate ring becomes a 5-membered ring, and when q is 1, the chelate
ring becomes a 6-membered ring.
[0075] R" represents an alkylene group having from 1 to 10 carbon atoms, a halogenated
alkylene group having from 1 to 10 carbon atoms, an arylene group having from 6 to 20
carbon atoms, or a halogenated arylene group having from 6 to 20 carbon atoms. These
alkylene group, halogenated alkylene group, arylene group and halogenated arylene group
may each contain a substituent or a heteroatom in the structure. Specifically, these groups
26
may each contain a halogen atom, a chain-lik or cyclic alkyl group, an aryl group, an alkenyl
group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a
carbonyl group, an acyl group, an amide group, or a hydroxyl group as a substituent, instead
of a hydrogen atom. Furthermore, these groups may also have a structure in which a
nitrogen atom, a sulfur atom or an oxygen atom is introduced instead of the carbon element.
Also, when q is 1 and m is 2 to 4, m units of R" may be bonded to each other. An example
thereof may be a ligand such as ethylenediamine tetraacetate.
[0076] R12 represents a halogen atom, an alkyl group having from 1 to 10 carbon atoms, a
halogenated alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20
carbon atoms, a halogenated aryl group having from 6 to 20 carbon atoms, or -Q 3R 13 (Q3 and
RI3 will be explained below).
These alkyl group, halogenated alkyl group, aryl group and halogenated aryl group
for R12 may each contain a substituent or a heteroatom in the structure as in the case of R",
and when n is 2 to 8, n units of RI2 may be bonded to each other to form a ring. RI2 is
preferably an electron-withdrawing group, and is particularly preferably a fluorine atom.
[0077] Q', Q2 and Q3 each independently represent 0, S or NR". That is, a ligand is
bonded to Y through these heteroatoms.
[0078] RI3 and RI4 each independently represent a hydrogen atom, an alkyl group having
fiom 1 to 10 carbon atoms, a halogenated alkyl group having from 1 to 10 carbon atoms, an
aryl group having from 6 to 20 carbon atoms, or a halogenated aryl group having from 6 to 20
carbon atoms. These alkyl group, halogenated alkyl group, aryl group and halogenated aryl
group may each contain a substituent or a heteroatom in the structure as in the case of R".
Furthermore, when there are plural RI3's or plural RI4's, the respective groups may be bonded
to each other to form a ring.
[0079] Examples of the alkali metal for M include lithium, sodium and potassium. Among
these, lithium is particularly preferred.
n is preferably an integer fiom 0 to 4.
[0080] When the non-aqueous electrolyte solution of the invention includes an electrolyte
compound represented by formula (V), the non-aqueous electrolyte solution of the invention
may include only one kind of the compound represented by formula (V), or may include two
or more kinds thereof.
Furthermore, the electrolyte compound represented by formula (V) is more
preferably at least one compound selected fiom the group consisting of a compound
represented by the following formula (VI), a compound represented by the following formula
(VII), a compound represented by the following formula (VIII), and a compound represented
by the following formula (IX). In regard to the compounds represented by formulas (VI) to
(IX), a compound in which M represents lithium, sodium or potassium may be mentioned as a
more preferred compound of the electrolyte compound represented by formula (V), and
particularly preferably, the electrolyte compound is a compound represented by formula
(VIII), in which M represents lithium.
[008 11
[0082] In formulas (VI) to (IX), M has the same definition as M in formula (V).
28
[0083] In regard to the method for synthesizing the electrolyte compound represented by
formula (V), for example, in the case of a compound represented by formula (VI), a method
of causing LiBF4 to react with a lithium alkoxide in a two-fold molar amount of LiBF4 in a
non-aqueous solvent, subsequently adding oxalic acid, and substituting the alkoxide bonded to
boron with oxalic acid, may be used.
Furthermore, in the case of a compound represented by formula (VII), a method of
causing LiPF6 to react with oxalic acid in a one-fold molar amount of this LiPF6 in a
non-aqueous solvent, and substituting the fluorine atom bonded to phosphorus with oxalic
acid, may be used.
Furthermore, in the case of a compound represented by formula (VIII), a method of
causing LiPFs to react with oxalic acid in a two-fold molar amount of this LiPF6 in a
non-aqueous solvent, and substituting the fluorine atom bonded to phosphorus with oxalic
acid, may be used.
Also, in the case of a compound represented by formula (IX), a method of causing
LiPF6 to react with oxalic acid in a 3-fold molar amount of this LiPF6 in a non-aqueous
solvent, and substituting the fluorine atom bonded to phosphorus with oxalic acid, may be
used.
In these cases, lithium salts of the anion compounds can be obtained.
[0084] When the non-aqueous electrolyte solution of the invention includes at least one of
the electrolyte compound represented by formula (V) or lithium difluorophosphate, the
content of at least one (if two or more kinds are included, the total content) of the electrolyte
compound represented by formula (V) or lithium difluorophosphate is preferably 0.001
mass% to 10 mass%, and more preferably in the range of 0.05 mass% to 5 mass%, relative to
the total mass of the non-aqueous electrolyte solution. When the content is in this range, a
balance can be achieved more effectively between an improvement in the low temperature
characteristics of a battery and an improvement in the storage characteristics of the battery.
[0085] Furthermore, when the non-aqueous electrolyte solution of the invention includes at
least one of the electrolyte compound represented by formula (V) or lithium
difluorophosphate, the content (if two or more kinds are included, the total content) of the
cyclic sulfate compound represented by formula (I) is preferably 0.001 mass% to 10 mass%,
and more preferably in the range of 0.05 mass% to 5 mass%, relative to the total mass of the
non-aqueous electrolyte solution. When the content is in this range, a balance can be
achieved more effectively between an improvement in the low temperature discharge
characteristics of a battery and an improvement in the storage characteristics of the battery.
e [0086] The non-aqueous electrolyte solution of the invention may also include other
components in addition to the cyclic sulfate compound represented by formula (I) (and at least
one of the electrolyte compound represented by formula (V) or lithium difluorophosphate that
are used according to necessity). Regarding the other components, any known components
can be optionally included.
The other components that are preferably included in the non-aqueous electrolyte
solution of the invention will be explained. The non-aqueous electrolyte solution generally
contains an electrolyte and a non-aqueous solvent.
[0087] Furthermore, an example of the other components that are preferably included in the
non-aqueous electrolyte solution of the invention may be at last one compound represented by
formula (X) shown below or formula (XI) shown below, from the viewpoint of obtaining the
effects of the invention more effectively.
[0088] [Non-aqueous solvent]
Regarding the non-aqueous solvent related to the invention, various known solvents
can be appropriately selected, but it is preferable to use a cyclic aprotic solvent andlor a linear
aprotic solvent.
When an increase in the flash point of the solvent is intended to enhance the safety of
the battery, it is preferable to use a cyclic aprotic solvent as the non-aqueous solvent.
[0089] [Cyclic aprotic solvent]
Examples of the cyclic aprotic solvent that can be used include a cyclic carbonate, a
cyclic carboxylic acid ester, a cyclic sulfone, and a cyclic ether.
The cyclic aprotic solvent may be used alone, or a mixture of plural kinds may also
be used.
The mixing proportion of the cyclic aprotic solvent in the non-aqueous solvent is 10
mass% to 100 mass%, more preferably 20 mass% to 90 mass%, and particularly preferably 30
mass% to 80 mass%. When such a ratio is employed, the conductivity of the electrolyte
solution that is related to the charge-discharge characteristics of the battery can be increased.
Specific examples of the cyclic carbonate include ethylene carbonate, propylene
carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and
2,3-pentylene carbonate. Among these, ethylene carbonate and propylene carbonate having
high dielectric constants are suitably used. In the case of a battery using graphite as the
negative electrode active material, ethylene carbonate is more preferable. Also, two or more
kinds of these cyclic carbonates may also be used in mixture.
[0090] Specific examples of the cyclic carboxylic acid ester include y-butyrolactone,
6-valerolactone, and alkyl-substituted forms such as methyl-y-butyrolactone,
ethyl-y-butyrolactone, and ethyl-6-valerolactone.
A cyclic carboxylic acid ester has a low vapor pressure, has low viscosity, has a high
dielectric constant, and can lower the viscosity of the electrolyte solution without decreasing
the flash point of the electrolyte solution and the degree of dissociation of the electrolyte.
For this reason, a cyclic carboxylic acid ester has a feature that the conductivity of the
electrolyte solution, which is an index associated with the discharge characteristics of a
battery, can be increased without increasing the inflammability of the electrolyte solution.
Therefore, in the case where an improvement in the flash point of the solvent is intended, it is
preferable to use a cyclic carboxylic acid ester as the cyclic aprotic solvent. Among cyclic
carboxylic acid esters, y-butyrolactone is most preferred.
Furthermore, it is preferable to use a cyclic carboxylic acid ester as a mixture with
another cyclic aprotic solvent. For example, a mixture of a cyclic carboxylic acid ester and a
cyclic carbonate andlor an acyclic carbonate may be used.
[0091] Examples of the cyclic sulfone include sulfolane, 2-methylsulfolane,
3-methylsulfolane, dimethylsulfone, diethylsulfone, dipropylsulfone, methylethylsulfone, and
methylpropylsulfone.
Examples of the cyclic ether include dioxolane.
[0092] [Acyclic aprotic solvent]
Examples of the acyclic aprotic solvent of the invention that can be used include an
acyclic carbonate, an acyclic carboxylic acid ester, an acyclic ether, and an acyclic phosphoric
acid ester.
The mixing proportion of the acyclic aprotic solvent in the non-aqueous solvent is 10
mass% to 100 mass%, more preferably 20 mass% to 90 mass%, and particularly preferably 30
mass% to 80 mass%.
Specific examples of the acyclic carbonate include dimethyl carbonate, methyl ethyl
carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl
propyl carbonate, dipropyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, dibutyl
carbonate, methyl pentyl carbonate, ethyl pentyl carbonate, dipentyl carbonate, methyl heptyl
carbonate, ethyl heptyl carbonate, diheptyl carbonate, methyl hexyl carbonate, ethyl hexyl
carbonate, dihexyl carbonate, methyl octyl carbonate, ethyl octyl carbonate, dioctyl carbonate,
and methyl trifluoroethyl carbonate. These acyclic carbonates may also be used as mixtures
of two or more kinds.
[0093] Specific examples of the acyclic carboxylic acid ester include methyl pivalate.
3 1
Specific examples of the acyclic ether include dimethoxyethane.
Specific examples of the acyclic phosphoric acid ester include trimethyl phosphate.
[0094] [Combination of solvents]
The non-aqueous solvent used in the non-aqueous electrolyte solution related to the
invention may be used singly or as a mixture of plural kinds. Furthermore, only cyclic
aprotic solvents may be used singly or as a combination of plural kinds; only acyclic aprotic
solvents may be used singly or as a combination of plural kinds; or mixtures of cyclic aprotic
solvents and acyclic protic solvents may also be used. Particularly when an enhancement of
the rate characteristics and the low temperature characteristics of the battery is intended, it is
preferable to use a cyclic aprotic solvent and an acyclic aprotic solvent in combination as the
non-aqueous solvent.
Furthermore, in view of the electrochemical stability of the electrolyte solution, it is
most preferable to apply a cyclic carbonate as the cyclic aprotic solvent, and to apply an
acyclic carbonate as the acyclic aprotic solvent. Furthermore, when a combination of a
cyclic carboxylic acid ester and a cyclic carbonate andlor acyclic carbonate is used, the
conductivity of the electrolyte solution related to the charge-discharge characteristics of the
battery can be increased.
[0095] Specific examples of the combination of a cyclic carbonate and an acyclic carbonate
include ethylene carbonate with dimethyl carbonate; ethylene carbonate with methyl ethyl
carbonate; ethylene carbonate with diethyl carbonate; propylene carbonate with dimethyl
carbonate; propylene carbonate with methyl ethyl carbonate; propylene carbonate with diethyl
carbonate; ethylene carbonate with propylene carbonate and methyl ethyl carbonate; ethylene
carbonate with propylene carbonate and diethyl carbonate; ethylene carbonate with dimethyl
carbonate and methyl ethyl carbonate; ethylene carbonate with dimethyl carbonate and diethyl
carbonate; ethylene carbonate with methyl ethyl carbonate and diethyl carbonate; ethylene
carbonate with dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate; ethylene
carbonate with propylene carbonate, dimethyl carbonate and methyl ethyl carbonate; ethylene
carbonate with propylene carbonate, dimethyl carbonate and diethyl carbonate; ethylene
carbonate with propylene carbonate, methyl ethyl carbonate and diethyl carbonate; and
ethylene carbonate with propylene carbonate, dimethyl carbonate, methyl ethyl carbonate and
diethyl carbonate.
The mixing proportion of the cyclic carbonate and the acyclic carbonate is such that
when expressed as a mass ratio, the ratio of cyclic carbonate : acyclic carbonate is 5 : 95 to
80 : 20, more preferably 10 : 90 to 70 : 30, and particularly preferably 15 : 85 to 55 : 45.
32
When such ratios are employed, an increase in the viscosity of the electrolyte solution is
suppressed, and the degree of dissociation of the electrolyte can be increased. Therefore, the
conductivity of the electrolyte solution related to the charge-discharge characteristics of a
battery can be increased. Furthermore, the solubility of the electrolyte can be further
increased. Accordingly, since an electrolyte solution having excellent electrical conductivity
at normal temperature or at a low temperature can be obtained, the rate characteristics of a
battery at normal temperature to a low temperature can be improved.
[0096] Specific examples of the combination of a cyclic carboxylic acid ester with a cyclic
carbonate and/or an acyclic carbonate include y-butyrolactone with ethylene carbonate;
y-butyrolactone with ethylene carbonate and dimethyl carbonate; y-butyrolactone with
ethylene carbonate and methyl ethyl carbonate; y-butyrolactone with ethylene carbonate and
diethyl carbonate; y-butyrolactone with propylene carbonate; y-butyrolactone with propylene
carbonate and dimethyl carbonate; y-butyrolactone with propylene carbonate and methyl ethyl
carbonate; y-butyrolactone with propylene carbonate and diethyl carbonate; y-butyrolactone
with ethylene carbonate and propylene carbonate; y-butyrolactone with ethylene carbonate,
propylene carbonate and dimethyl carbonate; y-butyrolactone with ethylene carbonate,
propylene carbonate and methyl ethyl carbonate; y-butyrolactone with ethylene carbonate,
propylene carbonate and diethyl carbonate; y-butyrolactone with ethylene carbonate, dimethyl
carbonate and methyl ethyl carbonate; y-butyrolactone with ethylene carbonate, dimethyl
carbonate and diethyl carbonate; y-butyrolactone with ethylene carbonate, methyl ethyl
carbonate and diethyl carbonate; y-butyrolactone with ethylene carbonate, dimethyl carbonate,
methyl ethyl carbonate, and diethyl carbonate; y-butyrolactone with ethylene carbonate,
propylene carbonate, dimethyl carbonate and methyl ethyl carbonate; y-butyrolactone with
ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate;
y-butyrolactone with ethylene carbonate, propylene carbonate, methyl ethyl carbonate, and
diethyl carbonate; y-butyrolactone with ethylene carbonate, propylene carbonate, dimethyl
carbonate, methyl ethyl carbonate, and diethyl carbonate; y-butyrolactone with sulfolane;
y-butyrolactone with ethylene carbonate and sulfolane; y-butyrolactone with propylene
carbonate and sulfolane; y-butyrolactone with ethylene carbonate, propylene carbonate and
sulfolane; and y-butyrolactone with sulfolane and dimethyl carbonate.
LO0971 [Other solvent]
The non-aqueous electrolyte solution related to the invention may also include
another solvent in addition to the solvents described above, as the non-aqueous solvent.
33
Specific examples of the other solvent include amides such as dimethylformamide; acyclic
carbamates such as methyl-N,N-dimethyl carbamate; cyclic arnides such as
N-methylpyrrolidone; cyclic ureas such as N,N-dimethylimidazolidinone; boron compounds
such as trimethyl borate, triethyl borate, tributyl borate, trioctyl borate, and trimethylsilyl
borate; and polyethylene glycol derivatives represented by the following formulas:
HO(CH2CH20)aH
HO[CH2CH(CH3)O]bH
CH30(CH2CH20),H
CH30[CH2CH(CH3)0]dH
CH30(CH2CH20)eCH3
CH30[CH2CH(CH3)O]&H3
C9HI9PhO(CH2CH2O),[CH(CH3)0]hCH3
(Ph represents a phenyl group)
CH30[CH2CH(CH3)O]iCO[OCH(CH3)CH2]jOCH3
In the above formulas, a to f each represent an integer from 5 to 250; g to j each
represent an integer from 2 to 249; 5 I g + h I 250; and 5 I i + j 1 250.
[0098] [Compound represented by formula (X)]
The non-aqueous electrolyte solution of the invention may contain a compound
represented by formula (X). An embodiment that the non-aqueous electrolyte solution of the
invention contains a compound represented by formula (X) is preferable from the viewpoint
of forming a passivation film of the negative electrode surface.
100991
[0100] In formula (X), YI and y2 each independently represent a hydrogen atom, a methyl
group, an ethyl group, or a propyl group.
[O 10 11 Examples of the compound represented by formula (X) include vinylene carbonate,
methylvinylene carbonate, ethylvinylene carbonate, propylvinylene carbonate,
dimethylvinylene carbonate, diethylvinylene carbonate, and dipropylvinylene carbonate.
Among these, vinylene carbonate is most preferred.
3 4
[0102] When the non-aqueous electrolyte solution of the invention contains the compound
represented by formula (X), the non-aqueous electrolyte solution of the invention may contain
only one kind of the compound represented by formula (X), or may contain two or more kinds
thereof.
The content (if two or more kinds are included, the total content) of the compound
represented by formula (X) can be appropriately selected in accordance with the purpose, but
the content is preferably 0.001 mass% to 10 mass%, and more preferably 0.05 mass% to 5
mass%, relative to the total mass of the non-aqueous electrolyte solution.
[O 1 031 [Compound represented by formula (XI)]
The non-aqueous electrolyte solution related to the invention may contain a
compound represented by formula (XI). An embodiment that the non-aqueous electrolyte
solution of the invention contains a compound represented by formula (XI) is preferable from
the viewpoint of forming a passivation film of the negative electrode surface.
[0 1 041
[0105] In formula (XI), x', x2, x3 and x4 each independently represent a hydrogen atom, a
fluorine atom, a chlorine atom, or an alkyl group having from 1 to 3 carbon atoms which may
be substituted with a fluorine atom, provided that X' to x4 are not both hydrogen atoms at the
same time.
[0106] In formula (XI), examples of the alkyl group having from 1 to 3 carbon atoms which
may be substituted with a fluorine atom as represented by X' to x4 include fluoromethyl,
difluoromethyl, trifluoromethyl, pentafluoroethyl, and heptafluoropropyl.
[0107] Regarding the compound represented by formula (XI), known compounds can be
used, and examples thereof include fluorinated ethylene carbonates in which 1 to 4 hydrogen
atoms of ethylene carbonate are substituted by fluorine atoms, such as 4-fluoroethylene
carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate,
4,4,5-trifluoroethylene carbonate, and 4,4,5,5-tetrafluoroethylene carbonate. Among these,
4,5-difluoroethylene carbonate and 4-fluoroethylene carbonate are most preferred.
[O108] When the non-aqueous electrolyte solution of the invention contains the compound
represented by het formula (XI), the non-aqueous electrolyte solution of the invention may
contain only one kind of the compound represented by formula (XI), or may contain two or
more kinds thereof.
The content (if two or more kinds are included, the total content) of the compound
represented by formula (XI) can be appropriately selected in accordance with the purpose, but
the content is preferably 0.001 mass% to 10 mass%, and more preferably 0.05 mass% to 5
mass%, relative to the total mass of the non-aqueous electrolyte solution.
[O 1091 [Electrolyte]
In the non-aqueous electrolyte solution of the invention, various electrolytes can be
used, and usually, any electrolyte which is used as an electrolyte for non-aqueous electrolyte
solutions can be used.
Regarding the electrolyte for the non-aqueous electrolyte solution of the invention, at
least one of the electrolyte compound represented by formula (V) or lithium
difluorophosphate may be used; another electrolyte having a structure that is different from
the structures of the electrolyte compound represented by formula (V) or lithium
difluorophosphate (hereinafter, also simply referred to as "other electrolyte") may be used; or
at least one of the electrolyte compound represented by formula (V) or lithium
difluorophosphate and another electrolyte may be used in combination.
Particularly, when the non-aqueous electrolyte solution of the invention contains at
least one of the electrolyte compound represented by formula (V) or lithium
difluorophosphate and another electrolyte, electrical conductivity which is a fundamental
performance of an electrolyte for conventional non-aqueous electrolyte solutions is retained,
and also, the battery performance (particularly, the low temperature discharge characteristics
of the battery in the early stage and during storage in a charged state) is also further enhanced.
Furthermore, when at least one of the electrolyte compound represented by formula (V),
lithium difluorophosphate, or the other electrolyte contains lithium ions, the relevant
compound serves as a stable supply source of lithium ions.
[0110] Specific examples of the other electrolyte include tetraalkylammonium salts such as
(C2H5)4NPF6, (C2H5)4NBF4, (C2H5)4NC104, (C2H5)4NAsF6, (C2H5)4N2SiF6,
(C2H5)4NOS02CkF(2k+l)( k = an integer from 1 to 8), and (C2H5)4NPFn[CkF(2k+l)]((n6 =- nan)
integer from 1 to 5, and k = an integer from 1 to 8); and lithium salts such as LiPF6, LiBF4,
LiC104, LiAsF6, Li2SiF6, LiOS02CkF(2k+(lk) = an integer from 1 to 8), and
LiPFn[CkF(2k+1)](6-(nn) = an integer from 1 to 5, and k = an integer from 1 to 8). Furthermore,
lithium salts represented by the following formula can also be used:
[O 1 1 1 1 L~C(SO~R')(SO~R~)(SOL~~RN~),( s ~ ~ ~ R ~ ~ )an(ds L~~~N(~soR~~R'~)~,)( so~R'~)
(wherein R7 to RI3 may be identical with or different from each other, and each represent a
perfluoroalkyl group having from 1 to 8 carbon atoms). These electrolytes may be used
singly, or two or more kinds may be used as mixtures.
Among these, lithium salts in particular are preferred, and LiPF6, LiBF4,
LiOS02CkF(2k+(lk) = an integer from 1 to 8), LiC1O4, LiAsF6, LiNS02[CkF(2k+1)(]k2 = an
integer from 1 to 8), and LiPF,[CkF(2k+l)](6(-nn )= an integer from 1 to 5, and k = an integer
from 1 to 8) are preferred.
An electrolyte is generally preferably included in the non-aqueous electrolyte at a
concentration of 0.1 mol/L to 3 mol/L, and preferably 0.5 mol/L to 2 mol/L.
[0112] In regard to the non-aqueous electrolyte solution of the invention, in the case of using
a cyclic carboxylic acid ester such as y-butyrolactone in combination as the non-aqueous
solvent, the non-aqueous electrolyte solution preferably contains LiPF6 in particular. Since
LiPF6 has a high degree of dissociation, LiPF6 can increase the conductivity of the electrolyte
solution, and also has an action of suppressing the reductive decomposition reaction of the
electrolyte solution on the negative electrode. LiPF6 may be used alone, or LiPF6 and
another electrolyte may be used together. Regarding the other electrolyte, any electrolytes
that are conventionally used as electrolytes for non-aqueous electrolyte solutions can all be
used; however, among the specific examples of lithium salts described above, a lithium salt
other than LiPF6 is preferred.
Specific examples thereof include LiPF6 with LiBF4, LiPF6 with LiN[S02CkF(2k+l)]2
(k = an integer from 1 to 8), LiPF6 with LiBF4 and L i N [ s o ~ c ~ F ( ~(k~ =+ a~n )in]t eger from 1 to
8).
[0113] The proportion of LiPF6 included in the lithium salts is preferably 1 mass% to 100
mass%, preferably 10 mass% to 100 mass%, and more preferably 50 mass% to 100 mass%.
Such an electrolyte is preferably included in the non-aqueous electrolyte solution at a
concentration of 0.1 molL to 3 mol/L, and preferably 0.5 mol/L to 2 mol/L.
The non-aqueous electrolyte solution of the invention is not only suitable as a
non-aqueous electrolyte solution for lithium secondary batteries, but can also be used as a
non-aqueous electrolyte solution for primary batteries, a non-aqueous electrolyte solution for
electrochemical capacitors, or an electrolyte solution for electric double layer capacitors or
aluminum electrolytic capacitors.
[O 1 141
The lithium secondary battery of the invention is constituted to basically include a
negative electrode, a positive electrode, and the non-aqueous electrolyte solution of the
invention, and usually, a separator is provided between the negative electrode and the positive
electrode.
[O 1 1 51 (Negative electrode)
As the negative electrode active material that constitutes the negative electrode, at
least one selected from metal lithium, a lithium-containing alloy, a metal or alloy capable of
alloying with lithium, an oxide capable of doping and dedoping of lithium ions, transition
metal nitrides capable of doping and dedoping of lithium ions, and a carbon material capable
of doping and dedoping of lithium ions (these may be used singly, or mixtures including two
or more kinds of these may also be used) can be used.
Examples of the metal or alloy capable of alloying with lithium (or lithium ions)
include silicon, a silicon alloy, tin, and a tin alloy. Furthermore, lithium titanate is also
acceptable.
Among these, a carbon material capable of doping and dedoping of lithium ions is
preferred. Examples of such a carbon material include carbon black, activated carbon, a
graphite material (artificial graphite or natural graphite), and an amorphous carbon material.
The form of the carbon material may be any of a fibrous form, a spherical form, a potato form
and a flake form.
[0116] Specific examples of the amorphous carbon material include hard carbon, cokes,
mesocarbon microbeads (MCMB) calcined at or below 1 500°C, and mesophase pitch carbon
fibers (MCF).
Examples of the graphite material include natural graphite and artificial graphite.
Regarding the artificial graphite, graphitized MCMB, graphitized MCF, and the like are used.
Furthermore, compounds containing boron can also be used as the graphite material. Also,
as the graphite material, a graphite material coated with a metal such as gold, platinum, silver,
copper or tin; a graphite material coated with an amorphous carbon; or a mixture of
amorphous carbon and graphite can also be used.
[0117] These carbon materials may be used singly, or two or more kinds may also be used as
mixtures.
The carbon material is particularly preferably a carbon material in which the
interplanar spacing d(002) of the (002) plane measured by an X-ray analysis is 0.340 nrn or
less. Furthermore, the carbon material is also preferably a graphite having a true density of
1.70 &m3 or greater, or a highly crystalline carbon material having properties close thereto.
38
When a carbon material such as described above is used, the energy density of the battery can
be further increased.
[0118] (Positive electrode)
Examples of the positive electrode active material that constitutes the positive
electrode include transition metal oxides or transition metal sulfides, such as MoS2, TiS2,
Mn02, and V205; composite oxides composed of lithium and transition metals, such as
LiCo02, LiMn02, LiMn204, L iNi02, LiNixCo(l-x102[0 < X < 11, and LiFeP04; and
electroconductive polymer materials such as polyaniline, polythiophene, polypyrrole,
polyacetylene, polyacene, dimercaptothiadiazole, and a polyaniline composite. Among these,
composite oxides composed of lithium and transition metals are particularly preferred.
When the negative electrode is formed of lithium metal or a lithium alloy, a carbon material
can be used as the positive electrode. Also, a mixture of a composite oxide of lithium and a
transition metal with a carbon material can be used as the positive electrode.
The positive electrode active materials described above may be used singly, or two or
more kinds may also be used as mixtures. If the positive electrode active material has
insufficient electroconductivity, the positive electrode can be constructed by using the positive
electrode active material together with an electroconductive aid. Examples of the
electroconductive aid include carbon materials such as carbon black, amorphous whiskers,
and graphite.
[O 1 1 91 (Separator)
The separator is a membrane which electrically insulates the positive electrode and
the negative electrode, and transmits lithium ions, and examples thereof include a porous film
and a polymer electrolyte.
As the porous film, a finely porous polymer film is suitably used, and examples of
materials of the porous film include polyolefins, polyimides, polyvinylidene fluoride, and
polyesters.
Particularly, porous polyolefins are preferred, and specific examples thereof include a
porous polyethylene film, a porous polypropylene film, and a multilayer film of a porous
polyethylene film and a porous polypropylene film. A porous polyolefin film may also have
another resin with excellent thermal stability coated thereon.
Examples of the polymer electrolyte include a polymer having a lithium salt
dissolved therein, and a polymer swollen with an electrolyte solution.
The non-aqueous electrolyte solution of the invention may also be used for the
purpose of obtaining a polymer electrolyte by swelling a polymer.
3 9
[O 1201 (Configuration of battery)
The lithium secondary battery of the invention includes the negative electrode active
material, positive electrode active material, and separator described above.
The lithium secondary battery of the invention can adopt various known shapes, and
the lithium secondary battery can be formed into a cylindrical shape, a coin shape, a
rectangular shape, a film shape, and any other shapes. However, the basic structure of the
battery is the same irrespective of the shape, and modifications in design can be applied in
accordance with the purpose.
An example of the non-aqueous electrolyte secondary battery of the invention may
be a coin cell as illustrated in FIG. 1.
In the coin cell illustrated in FIG. 1, a disc-shaped negative electrode 2, a separator 5
in which a non-aqueous electrolyte solution obtained by dissolving an electrolyte in a
non-aqueous solvent has been injected, a disc-shaped positive electrode 1, and optionally,
spacer plates 7 and 8 made of stainless steel, aluminum or the like, which are laminated in this
order, are accommodated between a positive electrode can 3 (hereinafter, also referred to as a
"battery can") and a sealing plate 4 (hereinafter, also referred to as a "battery can lid"). The
positive electrode can 3 and the sealing plate 4 are sealed by caulking with a gasket 6.
[0121] Meanwhile, the lithium secondary battery of the invention may be a lithium
secondary battery obtained by charging and discharging a lithium secondary battery (a lithium
secondary battery before being charged and discharged) which includes a negative electrode,
a positive electrode, and the non-aqueous electrolyte solution of the invention.
That is, the lithium secondary battery of the invention may be a lithium secondary
battery (a lithium secondary battery that has been charged and discharged) obtained by first
producing a lithium secondary battery before being charged and discharged, which includes a
negative electrode, a positive electrode and the non-aqueous electrolyte solution of the
invention, and subsequently charging and discharging one or more times the lithium
secondary battery before being charged and discharged.
[O122] There are no particular limitations on the use of the non-aqueous electrolyte solution
of the embodiments of the invention, and of a lithium secondary battery using the
non-aqueous electrolyte solution, and the electrolyte solution and the secondary battery can be
used in various known applications. For example, the electrolyte solution and the secondary
battery can be widely utilized in small-sized portable devices as well as in large-sized devices,
such as notebook computers, mobile computers, mobile telephones, headphone stereos, video
movie cameras, liquid crystal television sets, handy cleaners, electronic organizers,
motorcycles, electric motorcycles, bicycles, electric bicycles, illuminating devices, game
players, time pieces, electric tools, and cameras.
EXAMPLES
[0123] Hereinafter, the present invention will be more specifically described by way of
Examples, but the invention is not intended to be limited to these Examples. Meanwhile, in
the following Examples, the unit 'I%" indicates mass%.
LO1241 Hereinafter, Synthesis Examples of cyclic sulfate compounds represented by formula
(I) will be described.
[Synthesis Example 11

CLAIMS
1. A non-aqueous electrolyte solution, comprising:
a cyclic sulfate compound represented by the following formula (I):
wherein, in formula (I), R' represents a group represented by the above formula (11)
or a group represented by the above formula (111); and R2 represents a hydrogen atom, an
alkyl group having from 1 to 6 carbon atoms, a group represented by formula (11), or a group
represented by formula (111);
in formula (11), R~ represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding;
and
in a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
2. The non-aqueous electrolyte solution according to claim 1, wherein in formula
(I), R1 represents a group represented by formula (11) (provided that in formula (11), R3
represents a fluorine atom, an alkyl group having from 1 to 3 carbon atoms, a halogenated
alkyl group having from 1 to 3 carbon atoms, an alkoxy group having from 1 to 3 carbon
atoms, or a group represented by formula (IV)), or a group represented by formula (111); and
7 1
* R~ represents a hydrogen atom, an alkyl group having from 1 to 3 carbon atoms, a group
represented by formula (11) (provided that in formula (11), R3 represents a fluorine atom, an
alkyl group having from 1 to 3 carbon atoms, a halogenated alkyl group having from 1 to 3
carbon atoms, an alkoxy group having from 1 to 3 carbon atoms, or a group represented by
formula (IV)), or a group represented by formula (111).
3. The non-aqueous electrolyte solution according to claim 1 or 2, wherein in
formula (I), R' represents a group represented by formula (11) (provided that in formula (11),
R3 represents a fluorine atom, a methyl group, an ethyl group, a methoxy group, an ethoxy
group, or a group represented by formula (IV)), or a group represented by formula (111); and
R2 represents a hydrogen atom or a methyl group.
4. The non-aqueous electrolyte solution according to any one of claims 1 to 3,
wherein in formula (I), R' represents a group represented by formula (111), and R2 represents a
hydrogen atom.
5. The non-aqueous electrolyte solution according to any one of claims 1 to 4,
further comprising at least one of an electrolyte compound represented by the following
formula (V) or lithium difluorophosphate:
wherein, in formula (V), M represents an alkali metal; Y represents a transition
element, or an element of Group 13, Group 14 or Group 15 of the Periodic Table of Elements;
b represents an integer from 1 to 3; m represents an integer from 1 to 4; n represents an
integer from 0 to 8; q represents 0 or 1; R" represents an alkylene group having from 1 to 10
I
I carbon atoms, a halogenated alkylene group having from 1 to 10 carbon atoms, an arylene
I group having from 6 to 20 carbon atoms, or a halogenated arylene group having from 6 to 20
carbon atoms, wherein such groups may each contain a substituent or a heteroatom in the
structure, and when q is 1 and m is 2 to 4, m units of R" may be bonded to each other; R12
72
represents a halogen atom, an alkyl group having from 1 to 10 carbon atoms, a halogenated
alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20 carbon
atoms, a halogenated aryl group having from 6 to 20 carbon atoms, or -Q3 R 13, w herein such
groups, other than -Q3 R 13, may each contain a substituent or a heteroatom in the structure, and
when n represents an integer from 2 to 8, n units of R ' m~a y be bonded to each other to form a
ring; Q1, Q2, and Q3 each independently represent 0, S or NR"; and R" and R" each
independently represent a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, a
halogenated alkyl group having from 1 to 10 carbon atoms, an aryl group having from 6 to 20
carbon atoms, or a halogenated aryl group having from 6 to 20 carbon atoms, wherein such
groups may each contain a substituent or a heteroatom in the structure, and when plural RI3's
or plural RM's are present, the respective groups may be bonded to each other to form a ring.
6. The non-aqueous electrolyte solution according to claim 5, wherein the
electrolyte compound represented by formula (V) is at least one compound selected from the
group consisting of a compound represented by the following formula (VI), a compound
represented by the following formula (VII), a compound represented by the following formula
(VIII), and a compound represented by the following formula (IX):
wherein, in formulae (VI) to (IX), M has the same definition as M in formula (V).
7. The non-aqueous electrolyte solution according to any one of claims 1 to 6,
further comprising a compound represented by the following formula (X):
0
wherein, in formula (X), Y' and Y' each independently represent a hydrogen atom, a
methyl group, an ethyl group, or a propyl group.
74
8. The non-aqueous electrolyte solution according to any one of claims 1 to 7,
further comprising a compound represented by the following formula (XI):
wherein, in formula (XI), x', x2, x3 and X' each independently represent an alkyl
group, having from 1 to 3 carbon atoms, that may be substituted with a fluorine atom; a
hydrogen atom; a fluorine atom; or a chlorine atom, provided that X' to X' are not both
hydrogen atoms at the same time.
9. The non-aqueous electrolyte solution according to any one of claims 1 to 8,
wherein the content of the cyclic sulfate compound represented by formula (I) is from 0.001
mass% to 10 mass%.
10. The non-aqueous electrolyte solution according to claim 5, wherein the content
of at least one of the electrolyte compound represented by formula (V) or the lithium
difluorophosphate is from 0.001 mass% to 10 mass%.
11. The non-aqueous electrolyte solution according to claim 7, wherein the content
of the compound represented by formula (X) is from 0.001 mass% to 10 mass%.
12. The non-aqueous electrolyte solution according to claim 8, wherein the content
of the compound represented by formula (XI) is from 0.00 1 mass% to 10 mass%.
13. An additive for a lithium secondary battery, the additive comprising a cyclic
sulfate compound represented by the following formula (I) as an active ingredient:
wherein, in formula (I), R' represents a group represented by the above formula (11)
or a group represented by the above formula (111); and R2 represents a hydrogen atom, an
alkyl group having from 1 to 6 carbon atoms, a group represented by formula (11), or a group
represented by formula (111);
in formula (11), R~ represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding;
and
in a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
14. A cyclic sulfate compound represented by the following formula (I):
wherein, in formula (I), R' represents a group represented by the above formula (11)
or a group represented by the above formula (111); and R~ represents a hydrogen atom, an
alkyl group having from 1 to 6 carbon atoms, a group represented by formula (11), or a group
represented by formula (111);
in formula (11), R3 represents a halogen atom, an alkyl group having from 1 to 6
carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by the above formula (IV); and the
wavy line in formula (11), formula (111) and formula (IV) represents the position of bonding;
and
in a case in which there are two groups represented by formula (11) in the cyclic
sulfate compound represented by formula (I), the two groups represented by formula (11) may
be the same as or different from each other.
15. The cyclic sulfate compound according to claim 14, which is represented by the
following formula (XII):
wherein, in formula (XII), R2 represents a hydrogen atom or an alkyl group having
from 1 to 6 carbon atoms; and R3 represents a halogen atom, an alkyl group having from 1 to
6 carbon atoms, a halogenated alkyl group having from 1 to 6 carbon atoms, an alkoxy group
having from 1 to 6 carbon atoms, or a group represented by formula (IV).
16. The cyclic sulfate compound according to claim 15, wherein in formula (XII),
R2 represents a hydrogen atom or a methyl group; and R3 represents a fluorine atom, a methyl
group, an ethyl group, a methoxy group, an ethoxy group, or a group represented by formula
(IV).
17. The cyclic sulfate compound according to claim 15, which is
4-methylsulfonyloxymethyl-2,2-dioxo- 1,3,2-dioxathiolane,
4-ethylsulfonyloxymethyl-2,2-dioxo- 1,3 ,2-dioxathiolane, or
bis((2,2-dioxo- 1,3,2-dioxathiolane-4-y1)methyl) sulfate.
18. A lithium secondary battery, comprising:
a positive electrode;
a negative electrode including, as a negative electrode active material, at least one
selected from metal lithium, a lithium-containing alloy, a metal or alloy capable of alloying
with lithium, an oxide capable of doping and dedoping of lithium ions, transition metal
nitrides capable of doping and dedoping of lithium ions, or a carbon material capable of
doping and dedoping of lithium ions; and
the non-aqueous electrolyte solution according to any one of claims 1 to 12.
19. -- A lithium secondary battery obtained by charging or discharging a lithium
secondary battery that includes: a positive electrode; a negative electrode containing, as a
, negative electrode active material, at least one selected fiom metal lithium, a
lithium-containing alloy, a metal or alloy capable of alloying with lithium, an oxide capable of
doping and dedoping of lithium ions, transition metal nitrides capable of doping and dedoping
of lithium ions, or a carbon material capable of doping and dedoping of lithium ions; and the
non-aqueous electrolyte solution according to any one of claims 1 to 12.