Specification
【Technical Field】
This application claims the benefit of priority based on Korean Patent Application No.
10-2020-0131541, filed on October 13, 2020, and the entire contents of the Korean patent
application are incorporated herein by reference.
The present invention relates to a non-aqueous electrolyte solution for a lithium
10 secondary battery, and a lithium secondary battery including the same.
【Background Art】
Recently, the interest in developing energy storage technology is on the increase, and
as the applied fields are expanded to mobile phones, camcorders and laptop PCs, and electric
vehicles, efforts on the research and development of electrochemical elements are currently
15 embodied.
Among electrochemical devices, the interest in the development of secondary
batteries is on the increase, and particularly, lithium secondary batteries developed in 1990s
have been spotlighted with the advantages that the operating voltage is high and the energy
density is large.
20 In the case of a lithium secondary battery system, unlike an initial period when
2
lithium metal was directly applied to a system, a transition metal oxide containing lithium is
used as the positive electrode material, and carbon-based materials such as graphite and alloybased
materials such as silicon are applied to the negative electrode as the negative electrode
material. In this way, a system, in which lithium metal is not directly used in a battery, is
5 currently implemented.
Such a lithium secondary battery is composed of a positive electrode composed of a
transition metal oxide containing lithium, a negative electrode capable of storing lithium, an
electrolyte solution used for transferring lithium ions, and a separator. Herein, the electrolyte
solution is known as a component which significantly affects the stability and safety of the
10 battery, and a lot of researches on the electrolyte solution are currently conducted.
An electrolyte solution for a lithium secondary battery is composed of a lithium salt,
an organic solvent which dissolves the lithium salt, and a functional additive. Herein, in order
to improve electrochemical characteristics of the battery, it is important to appropriately select
these components.Examples of currently used lithium salt include LiPF6, LiBF4, LiFSI
15 (lithium fluorosulfonyl imide, LiN(SO2F)2), LiTFSI (lithium(bis)trifluoromethanesulfonyl
imide, LiN(SO2CF3)2) or LiBOB (lithium bis(oxalate) borate, LiB(C2O4)2), and examples of
the organic solvent include a carbonate-based organic solvent, an ester-based organic solvent,
or an ether-based organic solvent.
In the case of such a lithium secondary battery, the increase in the resistance and
20 reduction in the capacity during the charge/discharge and storage at a high temperature are
presented as a big problem in terms of deterioration of the performance. Herein, one of the
causes of such a problem is side reaction occurring due to deterioration at a high temperature,
3
particularly deterioration due to decomposition of salt at a high temperature. If the byproducts
of salt are activated and then decompose the film formed on the surface of the positive
electrode and the negative electrode terminal, the passivation capability of the film may drop,
thereby causing additional decomposition of the electrolyte solution and self-discharge.
In the case of an electrode material of a lithium i 5 on battery, particularly a negative
electrode, a graphite-based negative electrode is usually used. In the case of graphite, the
operation potential is equal to or less than 0.3V (vs. Li/Li+), and the currently used electrolyte
solution is reduced and decomposed. Such a reduction-decomposed product allows lithium
ions to be permeated, but the additional decomposition of the electrolyte solution forms a
10 solid electrolyte interphase (SEI) film.
Further, if the SEI film fails to have a passivation capability enough to suppress
additional decomposition of the electrolyte solution, the electrolyte solution is additionally
decomposed during storage, and the charged graphite is self-discharged, thereby showing a
phenomenon that the potential of the entire battery drops.
15 One of the elements, which can affect the passivation capability, HF and PF5, which
are generated by thermal decomposition of LiPF6 which is a lithium salt.As the surface of an
electrode or a film is deteriorated by the attack of such an acid, a transition metal is eluted in
the positive electrode, by which the resistance increases, and the redox center is lost, which
may decrease the capacity. Further, eluted metal ions are deposited on the negative electrode,
20 and the irreversible capacity increases by consumption of electrons due to deposition of metal
and additional electrolyte decomposition, thereby generating a cell capacity decrease and
causing a resistance increase and self-discharge of a graphite negative electrode.
4
Korean Patent Publication No. 10-2016-0004665 discloses that a non-aqueous
electrolyte solution, which contains a compound having a structure where functional groups
of an isocyanate group and a nitrile group coexist in one molecule, shows an effect of
suppressing a thickness change at a high temperature and cycle characteristics at a high
voltage of a lithium secondary battery.5 However, a compound, which was used in the example
of the above literature, did not show a satisfactory effect in terms of low voltage improvement.
As such, there is a need for a non-aqueous electrolyte solution which shows an effect
in low voltage improvement by suppressing precipitation in the negative electrode by forming
eluted transition metal ions and complex.
10 【Disclosure】
【Technical Problem】
The present invention is believed to solve at least some of the above problems. For
example, an aspect of the present invention provides a non-aqueous electrolyte solution for a
lithium secondary battery capable of showing effects in low voltage improvement by
15 suppressing transition metal precipitation in a negative electrode by being more strongly
deposited on the surface of a positive electrode, and a lithium secondary battery including the
non-aqueous electrolyte solution.
【Technical Solution】
A non-aqueous electrolyte solution according to the present invention for solving the
20 above problems includes: a lithium salt; an organic solvent; and a first additive, wherein the
first additive is one or two of compounds represented by following chemical formula 1a and
5
chemical formula 1b:
[Chemical formula 1a]
[Chemical formula 1b]
5
In an embodiment of the present invention, the first additive is a compound
represented by chemical formula 1a.
In an embodiment of the present invention, an amount of the first additive contained
in the electrolyte solution corresponds to 0.01 to 5 wt% of a total weight of the electrolyte
10 solution, and preferably 0.1 to 3 wt% of the total weight of the electrolyte solution.
In an embodiment of the present invention, the non-aqueous electrolyte solution of
the present invention may include a second additive, and the second additive includes at least
one selected from the group consisting of halogen-substituted or unsubstituted cyclic
carbonate compound, nitrile compound, phosphate compound, borate compound, sulfate
15 compound, sultone compound, amine compound, silane compound, benzene compound and
lithium compound. Preferably, the second additive may include vinylene carbonate and
6
propane sultone, and more preferably, the second additive may further include LiBF4.
In an embodiment of the present invention, an amount of the second additive
contained in the electrolyte solution corresponds to 0.01 to 10 wt% of a total weight of the
electrolyte solution.
5 In an embodiment of the present invention, the organic solvent includes one or a
combination of two or more selected from the group consisting of a carbonate compound, an
ether compound, an ester compound, a ketone compound, and an alcohol compound.
A lithium secondary battery of the present invention includes: a positive electrode; a
negative electrode; a separator; and the above-described non-aqueous electrolyte solution for
10 a lithium secondary battery.
【Advantageous Effects】
A first additive, which is contained in the non-aqueous electrolyte solution for a
lithium secondary battery of the present invention, shows an effect of improving a low voltage
by suppressing elution of a transition metal in a negative electrode by including an isocyanate
15 group and is excellent in high voltage and high temperature characteristics.
【Brief Description of the Drawings】
FIG. 1 is graph showing the experimental result of metal elution suppressing
evaluation.
【Detailed Description of the Preferred Embodiments】
20 Hereinafter, the present invention will be described in detail with reference to the
drawings. The terms and words used in the present specification and claims should not be
7
construed as limited to ordinary or dictionary terms and the inventor may properly define the
concept of the terms in order to best describe its invention. The terms and words should be
construed as meaning and concept consistent with the technical idea of the present invention.
Non-aqueous electrolyte 5 solution for lithium secondary battery
In an embodiment of the present invention, the present invention provides a nonaqueous
electrolyte solution for a lithium secondary battery, including: a lithium salt; an
organic solvent; and a first additive, in which the first additive is one or two of compounds
represented by following chemical formula 1a and chemical formula 1b:
10
[Chemical formula 1a]
[Chemical formula 1b]
15
8
(1) Lithium salt
In a non-aqueous electrolyte solution for a lithium secondary battery according to an
embodiment of the present invention, a lithium salt, which is commonly used in an electrolyte
solution for a lithium secondary battery may be used without limitation. For example, Li+ is
included as the cation of the lithium salt, a 5 nd at least one selected from the group consisting
of F-, Cl-, Br-, I-, NO3
-, N(CN)2
-, ClO4
-, BF4
-, B10Cl10
-, PF6
-, CF3SO3
-, CH3CO2
-, CF3CO2
-,
AsF6
-, SbF6
-, AlCl4
-, AlO4
-, CH3SO3
-, BF2C2O4
-, BC4O8
-, PF4C2O4
-, PF2C4O8
-, (CF3)2PF4
-,
(CF3)3PF3
-, (CF3)4PF2
-, (CF3)5PF-, C4F9SO3
-, CF3CF2SO3
-, (CF3SO2)2N-, (FSO2)2N-,
CF3CF2(CF3)2CO-, (CF3SO2)2CH-, (SF5)3C-, (CF3SO2)3C-, CF3(CF2)7SO3
-, SCN- and
10 (CF3CF2SO2)2N- may be included as the anion.
Specifically, the lithium salt may contain one or a combination of two or more
selected from the group consisting of LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiPF6,
LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, LiAlO4, LiCH3SO3, LiFSI
(lithium fluorosulfonyl imide, LiN(SO2F)2), LiTFSI (lithium
15 (bis)trifluoromethanesulfonimide, LiN(SO2CF3)2) and LiBETI (lithium
bisperfluoroethanesulfonimide, LiN(SO2C2F5)2).More specifically, the lithium salt may
contain one or a mixture of two or more selected from group consisting of LiPF6, LiBF4,
LiCH3CO2, LiCF3CO2, LiCH3SO3, LiFSI, LiTFSI and LiN(C2F5SO2)2.
The lithium salt can be appropriately changed within a typically available range, but
20 specifically, 0.1M to 3M lithium salt and more specifically 0.8M to 2.5M lithium salt may be
included in the electrolyte solution. If the concentration of the lithium salt exceeds 3M, the
viscosity of the non-aqueous electrolyte solution is increased, and the lithium ion transfer
9
effect is lowered and the non-aqueous electrolyte solution wettability is lowered, so that it is
difficult to form a SEI film having a uniform thickness on the surface of the electrode.
(2) Organic solvent
The organic solvent may 5 be minimized in decomposition by oxidation reaction during
the charge/discharge of the secondary battery, and there is no limit to the kind of the organic
solvent as long as it can show desired characteristics together with the additive. For example,
a carbonate organic solvent, an ether organic solvent or an ester organic solvent, and the like
can be used alone or in combination of two or more.
10 The carbonate organic solvent in the organic solvent may include at least one of a
cyclic carbonate organic solvent and a linear carbonate organic solvent. Specifically, the
cyclic carbonate-based organic solvent may include at least one selected from the group
consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-
butylene carbonate, 1,2-pentylalene carbonate, 2,3-pentylene carbonate, vinylene carbonate
15 and fluoroethylene carbonate (FEC), and may specifically include a mixed solvent of ethylene
carbonate having a high dielectric constant, and propylene carbonate having a relatively low
melting point, compared to ethylene carbonate.
Further, the linear carbonate-based organic solvent is a solvent having a low viscosity
and a low dielectric constant and may include at least one selected from the group consisting
20 of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl
carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and may specifically
include dimethyl carbonate.
10
In addition, as the ether-based organic solvent, any one selected from the group
consisting of dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl
ether, and ethylpropyl ether, or a mixture of two or more thereof may be used, but is not
limited thereto.
Th ester-based organic solvent may be 5 at least one selected from the group consisting
of a linear ester-based organic solvent and a cyclic ester-based organic solvent.
At this time, one or a mixture of two or more selected from the group consisting of
methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl
propionate, and butyl propionate may be used as the linear ester-based organic solvent, but the
10 present invention is not limited to these examples.
One or a mixture of two or more selected from the group consisting of γ-
butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone may be
used as the cyclic ester-based organic solvent, but the present invention is not limited to these
examples.
15 A cyclic carbonate-based organic solvent having a high viscosity capable of easily
dissociating lithium salt in the electrolyte due to a high dielectric constant may be used as the
organic solvent.Further, in order to manufacture an electrolyte having a higher electrical
conductivity, a linear carbonate compound and a linear ester compound having a low
viscosity and a low dielectric constant, such as dimethyl carbonate and diethyl carbonate, may
20 be mixed together with the cyclic carbonate-based organic solvent at an appropriate ratio.
More specifically, the organic solvent may be obtained by mixing the cyclic
carbonate compound with the linear carbonate compound, and the weight ratio of the cyclic
11
carbonate compound and the linear carbonate compound may be in the range of 10: 90 to 70:
30.
(3) First additive
Further, the non-aqueous electrolyte solut 5 ion for a lithium secondary battery of the
present invention contains one or two of compounds represented by chemical formula 1a and
chemical formula 1b below.
[Chemical formula 1a]
10 [Chemical formula 1b]
The functional group of the nitrile group contained in the compound represented by
chemical formula 1a and chemical formula 1b may be strongly bonded with the surface of the
positive electrode at a high temperature to form a complex, and the formed complex may act
15 as a protective film for blocking the activated portion of the surface of the positive electrode
and prevent a part of the transition metal from being eluted and precipitated in the negative
12
electrode during charge/discharge and may suppress gas generation and side reaction
occurring between the electrolyte solution and the positive electrode, thereby improving high
temperature performance characteristics.
Further, the functional group of the isocyanate group contained in the compound
represented by the chemical for 5 mula 1 is combined with a hydroxyl group existing on the
surface of the negative electrode composed of carbons and silicon and may significantly
improve the reliability at the time when a battery was preserved at a high temperature state for
a long time.
As shown in chemical formula 2a and chemical formula 2b, it is known that
10 compounds, which have a structure where functional groups of nitrile group and isocyanate
group are substituted in some substituents of alkylene group of carbon number 1 to 10, have
excellent high voltage and high temperature characteristics. However, the inventor of the
present invention have found that the effects of suppressing self-discharge according to metal
precipitation were much better when these functional groups substituted in a phenyl group are
15 more strongly bonded on the surface of the positive electrode and form a complex with
transition metal.
[Chemical formula 2a]
[Chemical formula 2b]
13
Further, in the first additive of the present invention, the low voltage suppressing
effects are different depending on the position of the functional group of the nitrile group and
the functional group of the isocyanate group. Specifically, th 5 e para-compound of chemical
formula 1a where these functional groups are substituted at the 1, 4 position of the phenyl
group shows more excellent effects of suppressing the low voltage than the metal compound
of the chemical formula 1b where the functional groups are substituted at 1, 3 position of the
phenyl group.Hence, in the present invention, the compound of the chemical formula 1a is
10 preferably selected as the first additive.
In a specific example of the present invention, an amount of the first additive
contained in the electrolyte solution corresponds to 0.01 to 5 wt%, preferably 0.1 to 3 wt%,
and more preferably 0.3 to 1.5 wt% of a total weight of the electrolyte solution.When the
content of the first additive is in the above range, secondary batteries having improved
15 performance can be manufactured. For example, in the range, the effects of removing byproducts
and the effects of suppressing metal elution are excellent, and accordingly, it is
possible to manufacture a secondary battery having improved a low voltage defect.
(3) Second additive
20 The non-aqueous electrolyte solution of the present invention may further include a
second additive which can form a stable film on the surface of the negative electrode and the
14
positive electrode or suppress decomposition of a solvent in the non-aqueous electrolyte
solution and act as a complementary element for improving mobility of lithium ions while not
significantly increasing the initial resistance in addition to the effects of the first additive by
being used together with the first additive.
Any additive for forming a 5 n SEI film capable of forming a stable film on the surface
of the positive electrode and the negative electrode terminal may be used as the second
additive.
Specifically, examples of the additive for forming the SEI film may include at least
one selected from the group consisting of halogen-substituted or unsubstituted cyclic
10 carbonate compound, nitrile compound, phosphate compound, borate compound, sulfate
compound, sultone compound, amine compound, silane compound, benzene compound and
lithium compound.
Specifically, the halogen-substituted cyclic carbonate compound or the halogenunsubstituted
cyclic carbonate compound may improve durability of the battery by forming a
15 stable SEI film on the surface of the negative electrode during battery activation.
Fluoroethylene carbonate (FEC) may be used as the halogen-substituted cyclic
carbonate compound, and vinylene carbonate (VC) or vinyl ethylene carbonate may be as the
halogen-unsubstituted cyclic carbonate compound.
The content of the halogen-substituted cyclic carbonate compound or the halogen20
unsubstituted cyclic carbonate compound may correspond to 5 wt% of the total weight of the
non-aqueous electrolyte solution.When the content of the cyclic carbonate compound in the
non-aqueous electrolyte solution exceeds 5 wt%, the cell swelling suppressing performance
15
and initial resistance may be deteriorated.
When the nitrile compound is used together with the above-described mixed additive,
effects of improvement of high temperature characteristics, etc. can be expected by
positive/negative electrode film stabilization. Namely, it may act as a supplementary element
in forming a negative 5 electrode SEI film, suppress decomposition of a solvent in the
electrolyte, and improve mobility of lithium ions. Examples of the nitrile compound may
include at least one selected from the group consisting of succinonitrile, adiponitrile,
acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile,
cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile,
10 difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-
fluorophenylacetonitrile, 1,4-dicyano-2-butene, glutaronitrile, 1,3,6-hexanetricarbonitrile, and
pimelonitrile.
The content of the nitrile compound may correspond to 8 or less wt% of the total
weight of the non-aqueous electrolyte solution.When the total content of the nitrile compound
15 in the non-aqueous electrolyte solution exceeds 8 wt%, the resistance increases due to the
increase of the film formed on the surface of the electrode, thereby deteriorating the
performance of the battery.
Further, since the phosphate compound stabilizes PF6 anions in the electrolyte
solution and helps formation of a positive electrode and negative electrode film, thereby
20 improving durability of the battery.Some examples of the phosphate-based compounds may
include at least one selected from the group consisting of lithium difluorophosphate (LiDFP,
LiPO2F2), lithium tetramethyl trimethyl silyl phosphate, trimethyl silyl phosphite (TMSPi),
16
trimethyl silyl phosphate (TMSPa), ethyl di(prop-2-yn-1-yl)phosphate, allyl diphosphate,
tris(2, 2,2-trifluoroethyl) phosphate (TFEPa) and tris(trifluoroethyl) phosphite, and the
content of the phosphate-based compound may correspond to 3 or less of the total weight of
the non-aqueous electrolyte solution.
The borate compound may 5 improve mobility of the lithium ions by promoting ion
pair separation, lower the interface resistance of the SEI film, and may solve problems such as
hydrofluoric acid gas generation by dissociating materials such as LiF, which are generated
during battery reaction and are not easily separated. LiBOB, LiB(C2O4)2, lithium
oxalyldifluoroborate, or tetramethyl trimethylsilylborate (TMSB) may be used as the borate
10 compound, and the content of the borate compound may be equal to or less than 3 wt% of the
total weight of the non-aqueous electrolyte solution.
At least one compound selected from the group consisting of 1,3-propane sultone
(PS), 1,4-butene sultone, ethane sultone, 1,3-propene sultone, and 1-methyl-1,3-propene
sultone may be used as the sultone compound, and the content of the sultone compound may
15 be in the range of 0.3 to 5 wt% and specifically 1 to 5 wt% of the total weight of the nonaqueous
electrolyte solution.When the content of the sultone-based compound in the nonaqueous
electrolyte solution exceeds 5 wt%, an excessively thick film may be formed on the
surface of the electrode, thereby increasing the resistance and deteriorating the output, and the
resistance may increase by a large amount of additives in the non-aqueous electrolyte solution,
20 thereby deteriorating the output characteristics.
The sulfate-based compound is a material which may be electrically decomposed and
may form a stable SEI film even at high temperature storage, and some examples thereof
17
include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyltrimethylene sulfate
(MTMS).
Triethanolamine or ethylene diamine may be used as the amine compound, and
tetravinylsilane may be used as the silane compound.
Monofluorobenzene (hereinafter, referred to as 5 "fluorobenzene"), difluorobenzene,
trifluorobenzene, tetrafluorobenzene, etc. may be used as the benzene compound.
Further, the lithium salt-based compound is a compound which is different from a
lithium salt contained in the non-aqueous electrolyte solution. Some examples of the lithium
salt-based compound include one or more selected from the group consisting of lithium
10 methylsulfate, lithium ethylsulfate, lithium 2-trifluoromethyl-4,5-dicyanoimidazole, lithium
tetrafluorooxalatophosphate, LiODFB and LiBF4, and the content of the lithium salt-based
compound may be equal to or less than 3 wt% of the total weight of the non-aqueous
electrolyte solution.
Two or more kinds of the second additives can be mixed and used, the content of the
15 second additives may correspond to 15 wt% or less, preferably 0.01 to 10 wt%, and more
preferably 0.1 to 5.0 wt% of the total weight of the electrolyte solution.
When the content of the second additive is less than 0.01 wt%, high temperature
storage characteristics and gas reduction effects, which are intended to be implemented from
the additive, are very weak, and if the content of the second additive exceeds 15 wt%, the side
20 reaction may excessively occur.In particular, when a large amount of second additives are
added, they may not be sufficiently decomposed and may remain in a precipitated or
unreacted state in the electrolyte solution at a room temperature. As such, the resistance
18
increases, and the lifespan characteristics of the secondary battery may be deteriorated.
Lithium secondary battery
Further, in an embodiment of the present invention, a lithium secondary battery
including a non-aqueous electrolyte solution for a secondary 5 battery of the present invention
is provided.
The lithium secondary battery of the present invention can be manufactured by
injecting the non-aqueous electrolyte solution of the present invention into an electrode
assembly which is obtained as a positive electrode, a negative electrode, and a separator
10 interposed between the positive electrode and the negative electrode are sequentially
laminated. At this time, a positive electrode, a negative electrode and a separator, which have
been commonly used in manufacturing a lithium secondary battery, may be used as the
positive electrode, the negative electrode, and the separator which form an electrode assembly.
Further, the positive electrode and the negative electrode, which form a lithium
15 secondary battery of the present invention, can be manufactured in a general method and used.
(1) positive electrode
The positive electrode may be manufactured by forming a positive electrode mixture
layer on a positive electrode current collector.The positive electrode mixture layer can be
20 formed by coating a positive electrode slurry, which includes a positive electrode active
material, a binder, a conductive material, and a solvent, on a positive electrode current
collector, and then drying the slurry and rolling the positive electrode current collector.
19
The positive electrode current collector is not particularly limited as long as it has
conductivity without causing a chemical change in the battery. Examples of the positive
electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon
or aluminum or stainless steel of which the surface has been treated with carbon, nickel,
5 titanium, silver, or the like.
The positive electrode active material is a compound capable of reversible
intercalation and deintercalation of lithium, and may specifically include a lithium metal
oxide containing lithium and at least one metal such as cobalt, manganese, nickel or
aluminum.Specifically, some examples of the lithium metal oxide may include lithium-nickel10
manganese-cobalt-based oxide (e.g., Li(NipCoqMnr1)O2 (herein, 0<p<1, 0<q<1, 0<r1<1,
p+q+r1=1), or Li(Nip1Coq1Mnr2)O4 (herein, 0<p1<2, 0<q1<2, 0<r2<2, p1+q1+r2=2),
etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Nip2Coq2Mnr3MS2)O2
(herein, M is one selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and
p2, q2, r3 and s2 are atomic fractions of respectively independent elements, and 0<p2<1,
15 0<q2<1, 0<r3<1, 0<s2<1, p2+q2+r3+s2=1), etc.).
Examples of the positive electrode active material may include Li(Ni1/3Mn1/3Co1/3)O2,
Li(Ni0.35Mn0.28Co0.37)O2, Li(Ni0.6Mn0.2Co0.2)O2,Li(Ni0.5Mn0.3Co0.2)O2, Li(Ni0.7Mn0.15Co0.15)O2,
Li(Ni0.8Mn0.1Co0.1)O2 or Li(Ni0.8Co0.15Al0.05)O2.
The content of the positive electrode active material may correspond to 90 to 99 wt%
20 and specifically 93 to 98 wt% of the total weight of solids in the positive electrode slurry.
The binder is added in an amount of 1 to 30% by weight, on the basis of the total
20
weight of solids in the positive electrode slurry, as a component that assists in bonding
between the active material and the conductive material and bonding to the current
collector.Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol,
carboxymethylcellulose, starch, hydroxypropylcellulose, regenerated cellulose,
polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, 5 ethylene-propylenediene
terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene butadiene rubber,
fluorine rubber, and various copolymers.
Such a conductive material is not particularly limited as long as it has electrical
conductivity without causing a chemical change in the battery, and examples thereof include:
10 carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace
black, lamp black, or thermal black; graphite powders such as natural graphite or artificial
graphite, or graphite, of which the crystal structure has been very much developed; conductive
fibers such as carbon fiber and metal fiber; conductive powders such as carbon fluoride,
aluminum and nickel powder; conductive whiskey such as zinc oxide and potassium titanate;
15 conductive metal oxides such as titanium oxide; and conductive materials such as
polyphenylene derivatives and the like.
The conductive material is usually added in an amount of 1 to 30% by weight based
on the total weight of solids in the positive electrode slurry.
The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone),
20 and may be used in an amount that becomes a desirable viscosity when the positive electrode
active material and optionally a binder and a conductive material are included. For example,
the concentration of the solids in the slurry containing the positive electrode active material
21
and, optionally, the binder and the conductive material may be in an amount of 10 wt% to 70
wt%, preferably 20 wt% to 60 wt%.
(2) negative electrode
The negative electrode may be manufactured by 5 forming a negative electrode mixture
layer on a negative electrode current collector.The negative electrode mixture layer may be
formed by coating a slurry including a negative electrode active material, a binder, a
conductive material, a solvent, and the like on a negative electrode current collector, followed
by drying and rolling.
10 The negative electrode current collector is generally made to a thickness of 3 to 500
micrometers.The negative electrode current collector is not particularly limited as long as it
has high electrical conductivity without causing chemical changes in the battery, and
examples thereof include copper, stainless steel, aluminum, nickel, titanium, sintered carbon,
copper or stainless steel of which the surface has been treated with carbon, nickel, titanium,
15 silver or the like, aluminum-cadmium alloy, or the like.In addition, like the positive electrode
current collector, fine unevenness can be formed on the surface to enhance the bonding force
of the negative electrode active material, and it can be used in various forms such as a film, a
sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.
Further, the negative electrode active material may include at least one selected from
20 the group consisting of lithium metal, a carbon material capable of reversibly
intercalating/deintercalating lithium ions, metal or an alloy of a metal and lithium, a metal
oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.
22
Any carbon-based negative electrode active material, which is generally used in a
lithium ion secondary battery, may be used as a carbon material capable of reversibly
intercalating/deintercalating the lithium ions, and representative examples thereof may
include crystalline carbon, amorphous carbon, or a combination thereof. Some examples of
the crystalline carbon may include amorphous, f 5 laky, spherical, or fibrous natural graphite or
artificial graphite, and some examples of the amorphous carbon may include soft carbon, hard
carbon, mesophase pitch carbide, and calcined coke.
A metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca,
Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn, or an alloy of lithium and these metals may be
10 used.
One selected from the group consisting of PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4,
Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), and SnxMe1-
xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, group 1, group 2 and group 3 elements of the
periodic table, halogen; 0
Documents
Application Documents
| # |
Name |
Date |
| 1 |
202217054719.pdf |
2022-09-23 |
| 2 |
202217054719-TRANSLATIOIN OF PRIOIRTY DOCUMENTS ETC. [23-09-2022(online)].pdf |
2022-09-23 |
| 3 |
202217054719-STATEMENT OF UNDERTAKING (FORM 3) [23-09-2022(online)].pdf |
2022-09-23 |
| 4 |
202217054719-PROOF OF RIGHT [23-09-2022(online)].pdf |
2022-09-23 |
| 5 |
202217054719-PRIORITY DOCUMENTS [23-09-2022(online)].pdf |
2022-09-23 |
| 6 |
202217054719-POWER OF AUTHORITY [23-09-2022(online)].pdf |
2022-09-23 |
| 7 |
202217054719-FORM 1 [23-09-2022(online)].pdf |
2022-09-23 |
| 8 |
202217054719-DRAWINGS [23-09-2022(online)].pdf |
2022-09-23 |
| 9 |
202217054719-DECLARATION OF INVENTORSHIP (FORM 5) [23-09-2022(online)].pdf |
2022-09-23 |
| 10 |
202217054719-COMPLETE SPECIFICATION [23-09-2022(online)].pdf |
2022-09-23 |
| 11 |
202217054719-FORM 3 [26-12-2022(online)].pdf |
2022-12-26 |
| 12 |
202217054719-FORM 18 [15-04-2024(online)].pdf |
2024-04-15 |