TECHNICAL FIELD
The present invention relates to an anode-less lithium ion battery comprising
a) a cathode comprising a cathode current collector and a cathode electro-active
material on the cathode current collector; b) an anode current collector; c) a
10 liquid electrolyte composition between the a) cathode and the b) anode current
collector; and d) a separator, wherein the c) liquid electrolyte composition
comprises i) at least 70% by volume (vol%) of a solvent mixture with respect to
the total volume of the electrolyte composition, comprising at least one fluorinated
ether compound and at least one non-fluorinated ether compound, and ii) at least
15 one lithium salt.
BACKGROUND OF THE INVENTION
For more than two decades, lithium-ion batteries have retained a dominant
position in the market of rechargeable energy storage devices due to their many
20 benefits comprising light-weight, reasonable energy density, and good cycle life.
Nevertheless, current lithium-ion batteries still suffer from relatively low energy
densities with respect to the required energy density, which is increasing for high
power applications such as electrical vehicles (EV s ), hybrid electrical vehicles
(HEVs), grid energy storage, etc.
25 In general, lithium-ion batteries have various components comprising an
anode current collector, an anode material, an electrolyte, a separator, a cathode
material, a cathode current collector and a housing. Since various components are
used, lithium-ion batteries are manufactured through a large number of steps. An
anode of a lithium-ion battery is generally formed by applying an electro-active
30 material onto an anode current collector to produce an active material layer which
may comprise an active material, conducting material, and a binder.
Employing lithium metal as the anode material has been known since the
1970s. Indeed, lithium metal has favorable characteristics thanks to its low redox
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potential and high specific capacity, i.e., about 3861 mAh g-1. However, these cells
have not achieved commercial success due to the following two main drawbacks:
First, lithium metal dendrites may form during the operation of the cell.
They tend to accumulate in the cell, puncture the separator and cause an internal
5 short-circuit, leading to heat and possibly fire or explosion.
Second, during the initial cycles, the solid electrolyte interface (SEI) layer
forms on the anode surface, causing significant Coulombic efficiency losses, and
an increase of the cell resistance. Although such low Coulombic efficiency may
be partially compensated by having an excess amount of Li metal, the dendrite
10 growth-related battery failures with high safety risk have been a big obstacle in
the industry.
Accordingly, diverse research efforts have been engaged with a view of
reducing or suppressing the lithium dendrite formation and improving the cycling
performance ofthe cell.
15 The use of a solid polymer electrolyte has been considered in place of a
liquid electrolyte. For example, S. Liu et al. in Journal of Power Sources,
195, 6847 (2010) describe a lithium electrochemical cell comprising a lithium ion
conducting polymer electrolyte of polyethylene oxide PE01s with lithium
trifluoromethane sulfonimide LiN(CF3S02)2 (LiTFSI). However, short-circuits
20 have been observed even with such a solid polymer, although to a lesser extent
than with a liquid electrolyte. Besides, no polymer electrolyte with high
conductivity at room temperature has been reported yet.
Hydro-Quebec and 3M have recently developed lithium electrochemical
cells comprising a polymer electrolyte, an anode made of a thin lithium foil and a
25 cathode containing vanadium oxide as the electro-active material. However,
accidents have been reported on these cells, which were probably caused by the
formation of dendrites during the charging process.
The use of a solid electrolyte has also been considered instead of a liquid
electrolyte. For example R. Sudo et al. describe in Solid State Ionics, 262, 151
30 (2014) the use of Al-doped Li7La3Zr2012 as a solid electrolyte in an
electrochemical cell comprising a lithium anode. However, lithium dendrites were
again observed.
Many approaches to the prevention of lithium dendrite formation have
focused on improving the stability and uniformity of the passivation layer on the
35 anode. For example, D. Aurbach et al. in Solid State Ionics, 148, 405 (2002) and
H. Ota et al. in Electrochimica Acta, 49, 565 (2004) report that additives such as
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C02, S02, and vinylene carbonate help in improving the stability of the passivation
layer, However, these additives are consumed during the operation of the cell.
Thus, they do not offer a long-term solution to the problem of dendrite formation.
There have been also some approaches consisting of modifying the
5 composition ofthe liquid electrolyte.
For example, the use of a liquid electrolyte with a high lithium salt
concentration of LiTFSI in dimethoxyethane (DME)-1,3dioxolane (DOL)
(1: 1 v:v) for suppressing lithium dendrite formation has been described by L. Suo
et al. in Nature Communications, DOI:10.1038/ncomms2513 (2013).
10 The use of a liquid electrolyte with a high lithium salt concentration of
lithium bis(fluorosulfonyl)imide LiN(FS02)2 (LiFSI) in dimethoxyethane (DME)-
1,3dioxolane (DOL) (1: 1 v:v) for enabling high-rate cycling of a lithium metal
electrode without dendrite growth has been described by J. Qian et al. in Nature
Communications, DOl: 10.1038/ncomms7362 (2015).
15 H. Wang et al. report in ChemElectroChem, 2, 1144 (20 15) that a cell
containing lithium metal as the anode and a solvated ionic liquid of tetraglyme
(G4) and LiFSI as the electrolyte exhibits excellent cycling performance.
Another approach to finding a remedy to the growth of lithium dendrites at
the surface of the anode is an anode-less lithium ion battery. In an anode-free
20 battery, the energy density may be significantly greater than that of conventional
lithium-ion batteries, even in consideration of the thickness increase of the anode
due to the lithium plating made via charging.
In this regard, in addition to the structural differences, the main differences
between a lithium metal battery and an anode-less battery include the following:
25 i) the charge/discharge mechanisms in an anode-free battery are totally
different from conventional rechargeable batteries due to the absence of anode.
For an anode-less battery, despite neither lithium foil nor other anodes are used,
lithium is absolutely necessary for cathode because the lithium metal on anode
current collector is obtained from lithium transition metal oxides, e.g., LiCo02,
30 NCMs (LiNixCoyMnz02), etc. More specifically, lithium ions extracted from the
cathode electrolyte soaked separator are electroplated onto the surface of an anode
current collector, forming a deposited lithium together with an electrochemically
stable solid electrolyte interphase (SEI) during the charging process. The
deposited lithium is the only available lithium sources for discharge. From this
35 reason, the safety harzard often posed in the lithium metal battery is greatly
reduced because there is no active lithium source at the anode side; and
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ii) the kinetic of the electrochemical process of an anode-less battery is
different from a lithium battery. That is, in an anode-less battery, lithium is directly
plated on the bare surface of an anode current collector from cathode in its first
charging, while for a lithium metal battery, lithium is deposited on lithium foil
5 which easily leads to the dendrite growth. Moreover, the side reaction with
conventional liquid electrolytes is getting much more severe. This finally brings
an anode swelling via repeated breaking and repairing the SEI layers, that hinders
industrialization.
For now, such an anode-free cell uses conventional liquid electrolytes such
10 as a carbonate-based electrolyte or an ether-based electrolyte having a low
viscosity and a high ionic conductivity. These liquid electrolytes decompose to
make a passivation layer at the beginning of the cycles, which will result in the
dendrite growth, and also further side reactions between the electrolyte and the
deposited reactive lithium-ions. This has been one of the critical issues to block
15 the commercialization of the anode-free cells. Accordingly, despite various
advantages of an anode-less battery, those challenges resulting from the
fundamental issues in lithium plating/stripping processes have forced the persons
skilled in the field to investigate more diverse strategies including new designs in
an anode current collector with low overpotential and uniform electric field, and
20 the engineering of SEI layer by optimizing electrolytes to induce the formation of
stable and robust SEI layer through the selection of the proper solvents, additives,
salts, etc. in optimal concentrations. In other words, even though after the initial
charge process, an anode-less battery operates as a lithium metal battery, it doesn
not mean that the whole cell structure, the working mechanisms, and the optimal
25 electrolytes for a lithium metal battery are identical to those for an anode-less
battery. Thus, there remains a need for an anode-free lithium ion battery having
improved cell performance, while minimizing the dendrite growth and the side
reactions between the liquid electrolyte and lithium plated anode, and also for an
liquid electrolyte which may mitigate such drawbacks while maintaining good cell
30 performance of an anode-less battery.
SUMMARY OF THE INVENTION
The present invention relates to an anode-less lithium Ion battery
compnsmg:
35 a) a cathode comprising a cathode current collector and a cathode electroactive
material on the cathode current collector;
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b) an anode current collector;
c) a liquid electrolyte composition between the a) cathode and the b) anode
current collector; and
d) a separator,
5 wherein the c) liquid electrolyte composition comprises i) at least 70% by
volume (vol%) of a solvent mixture with respect to the total volume of the
electrolyte composition, comprising at least one fluorinated ether compound and
at least one non-fluorinated ether compound, and ii) at least one lithium salt.
It was surprisingly found by the inventors that the above-mentioned
10 technical problems can be solved by using a liquid electrolyte composition
according to the present invention within an anode-less lithium ion battery.
BRIEF DESCRIPTION OF DRA WNINGS
Figure 1 shows cycle retention (%) of NCM523/Cu cells with electrolyte
15 compositions ofE1-E2 and CE1-CE4 at 3.6~4.2V (0.2C/0.5C).
Figure 2 shows Coulombic efficiency vs. cycle number ofNCM523/Cu cells
with electrolyte compositions ofE1-E2 and CE1-CE4 at 3.6~4.2V (0.2C/0.5C).
DETAILED DESCRIPTION OF THE INVENTION
20 DEFINITIONS
Throughout this specification, unless the context requires otherwise, the
word "comprise" or "include", or variations such as "comprises", "comprising",
"includes", including" will be understood to imply the inclusion of a stated
element or method step or group of elements or method steps, but not the exclusion
25 of any other element or method step or group of elements or method steps.
According to preferred embodiments, the word "comprise" and "include", and
their variations mean "consist exclusively of'.
As used in this specification, the singular forms "a", "an" and "the" include
plural aspects unless the context clearly dictates otherwise. The term "and/or"
30 includes the meanings "and", "or" and also all the other possible combinations of
the elements connected to this term.
The term "between" should be understood as being inclusive of the limits.
As used herein, "alkyl" groups include saturated hydrocarbons having one
or more carbon atoms, including straight-chain alkyl groups, such as methyl, ethyl,
3 5 propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclic alkyl groups (or
"cycloalkyl" or "alicyclic" or "carbocyclic" groups), such as cyclopropyl,
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cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl, branched-chain alkyl
groups, such as isopropyl, tert-butyl, sec-butyl, and isobutyl, and alkyl-substituted
alkyl groups, such as alkyl-substituted cycloalkyl groups and cycloalkylsubstituted
alkyl groups.
5 The term "aliphatic group" includes organic moieties characterized by
straight or branched-chains, typically having between 1 and 18 carbon atoms. In
complex structures, the chains may be branched, bridged, or cross-linked.
Aliphatic groups include alkyl groups, alkenyl groups, and alkynyl groups.
As used herein, the terminology "(Cn-Cm)" in reference to an organic group,
10 wherein nand mare integers, respectively, indicates that the group may contain
from n carbon atoms tom carbon atoms per group.
Ratios, concentrations, amounts, and other numerical data may be presented
herein in a range format. It is to be understood that such range format is used
merely for convenience and brevity and should be interpreted flexibly to include
15 not only the numerical values explicitly recited as the limits of the range, but also
to include all the individual numerical values or sub-ranges encompassed within
that range as if each numerical value and sub-range is explicitly recited. For
example, a temperature range of about 120°C to about 150°C should be interpreted
to include not only the explicitly recited limits of about 120°C to about 150°C, but
20 also to include sub-ranges, such as l25°C to 145°C, 130°C to 150°C, and so forth,
as well as individual amounts, including fractional amounts, within the specified
ranges, such as 122.2°C, 140.6°C, and 141.3°C, for example.
Unless otherwise specified, in the context of the present invention the
amount of a component in a composition is indicated as the ratio between the
25 volume of the component and the total volume of the composition multiplied by
100, i.e.,% by volume (vol%) or as the ratio between the weight of the component
and the total weight of the composition multiplied by 100, i.e.,% by weight (wt%).
The constituents of the anode-less lithium ion battery comprising a) a
cathode comprising a cathode current collector and a cathode electro-active
30 material on the cathode current collector; b) an anode current collector; c) a liquid
electrolyte composition; and d) a separator according to the present invention are
described hereinafter in details. It is to be understood that both the foregoing
general description and the following detailed description are exemplary and are
intended to provide further explanation of the invention as claimed. Accordingly,
35 various changes and modifications described herein will be apparent to those
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skilled in the art. Moreover, descriptions of well-known functions and
constructions may be omitted for clarity and conciseness.
The present invention relates to an anode-less lithium ion battery
compnsmg:
5 a) a cathode comprising a cathode current collector and a cathode electroactive
material on the cathode current collector;
b) an anode current collector;
c) a liquid electrolyte composition between the a) cathode and the b) anode
current collector; and
10 d) a separator,
wherein the c) liquid electrolyte composition comprises i) at least 70% by
volume (vol%) of a solvent mixture with respect to the total volume of the
electrolyte composition, comprising at least one fluorinated ether compound and
at least one non-fluorinated ether compound, and ii) at least one lithium salt.
15 In one embodiment, the solvent mixture according to the present invention
compnses
- from 60 to 90 vol% of at least one fluorinated ether compound; and
-from 10 to 40 vol% of at least one non-fluorinated ether compound, with
respect to the total volume of the solvent mixture.
20 In another embodiment, the solvent mixture according to the present
invention comprises
- from 80 to 90 vol% of at least one fluorinated ether compound; and
-from 10 to 20 vol% of at least one non-fluorinated ether compound, with
respect to the total volume of the solvent mixture.
25 In one embodiment, the solvent mixture according to the present invention
is free from an organic carbonate.
Non-limiting examples of the organic carbonate include, notably, ethylene
carbonate (1 ,3-dioxolan-2-one ), propylene carbonate, 4-methylene-1 ,3-dioxolan-
2-one, 4,5-dimethylene-1,3-dioxolan-2-one, dimethyl carbonate, diethyl
30 carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate,
methyl butyl carbonate, ethyle propyl carbonate, ethyl butyl carbonate, propyl
butyl carbonate, dibutyl carbonate, di-tert-butyl carbonate, butylene carbonate,
mono- and difluorinated propylene carbonate, mono- and difluorinated butylene
carbonate, 3,3,3-trifluoropropylene carbonate, fluorinated dimethyl carbonate,
35 fluorinated diethyl carbonate, fluorinated ethyl methyl carbonate, fluorinated
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dipropyl carbonate, fluorinated dibutyl carbonate, fluorinated methyl propyl
carbonate, and fluorinated ethyl propyl carbonate.
In the present invention, the term "fluorinated ether compound" is intended
to denote an ether compound, wherein at least one hydrogen atom is replaced by
5 fluorine. One, two, three or a higher number of hydrogen atoms may be replaced
by fluorine.
In the present invention, the fluorinated ether compound compnses
fluorinated mono-ether compounds, fluorinated di-ether compounds and
fluorinated tri-ether compounds.
10 In one embodiment, the fluorinated ether compound according to the present
invention is an aliphatic compound.
In one embodiment, the fluorinated ether compound has a chemical formula
ofCaFbHcOct, wherein a,b,c and dare all integers, dis an integer from 1 to 3, a is
an integer from 3 to 10, preferably from 4 to 7, and 2*(a+ 1) = b+c.
15 In a preferred embodiment, the fluorinated ether compound is selected from
the group consisting of:
i) 1,1 ,2,2-tetrafluoroethyl-2,2,3,3 -tetrafluoropropyl ether (TTE), 1,1 ,3,3-
tetrafluoro-1-(1, 1 ,2,2-tetrafluoroethoxy) propane, 1,1, 1 ,3,3-pentafluoro-3-(2,2,2-
trifluoroethoxy) propane, 1, 1, 1,3,3-pentafluoro-3-(1, 1,3,3,3-
20 pentafluoropropoxy)propane, 1,1 '-oxybis(l, 1,2,2-tetrafluoroethane), 1, 1, 1,3,3-
pentafluoro-3-methoxy-2-(trifluoromethyl) propane, 1, 1, 1,3,3-pentafluoro-3-
( fl uoromethoxy )-2-( trifl uoromethy l)propane, 2,2-difl uoro-2-methoxy -1, 1-
bis(trifluoromethyl)ethane, 2-(ethoxy difluoromethyl)-1, 1, 1,3,3,3-
hexafl uoropropane, 2-( difluoropropoxy methyl )-1, 1, 1, 3,3, 3-hexafl uoropropane,
25 1, I-bis( difluoromethoxy )-1 ,2,2,2-tetrafluoroethane, 1,1 ,2,2-tetrafluoro-3-
( 1, 1 ,2,2-tetrafluoroethoxy) propane, 1-(2,2-difluoroethoxy )-1, 1 ,2,3 ,3 ,3-
hexafl uoropropane, 1, 1 ,2,2, 3-pentafl uoro-3 -( 1, 1 ,2,2-tetrafluoroethoxy )propane,
1-(3, 3 -difl uoropropoxy )-1, 1 ,2,3 ,3, 3-hexafluoropropane, 1-[ difl uoro( 1, 1 ,2,2-
30
tetrafluoroethoxy)methoxy ]-1, 1 ,2,2,2-pentafluoroethane,
[ ( difluoromethylene )bis( oxy )]bis(l, 1 ,2,2,2-pentafluoroethane ),
1,1'-
1,1,1,3,3,3-
hexafluoro-2-fluoromethoxymethoxy propane, pentafluoro[ 1 ,2,2,2-tetrafluoro-1-
(trifluoromethoxy)ethoxy ]ethane, 1,1 ,2,3,3-pentafluoro-1 ,3-dimethoxypropane,
1, 1 ,2,2,3, 3-hexafl uoro-1-methoxy-3-trifl uoromethoxypropane, 1, 1 '-
[ ( difluoromethylene )bis( oxy) ]-bis(2,2,2-trifluoroethane ), 1,2-
3 5 bis( difluoromethoxy )-1, 1 ,2,2-tetrafluoroethane, [2-( difluoromethoxy )-1, 1 ,2,2-
tetrafluoroethoxy] difl uoromethane, 1-[ difl uoro( trifl uoromethoxy )methoxy]-
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1,1 ,2,2-tetrafluoro-2-methoxyethane, 1-( difluoromethoxymethoxy )-1, 1 ,2,2-
tetrafluoro-2-(trifluoromethoxy )ethane, 1-[ ( difluoromethoxy )difluoromethoxy ]-
1, 1 ,2,2-tetrafluoro-2-methoxyethane, and 1-( difluoromethoxy )-2-
[ ( difluoromethoxy )difluoromethoxy ]-1, 1 ,2,2-tetrafluoroethane;
5 ii) chemical compounds represented by the general formula (A),
10 wherein X isH or F; and
iii) mixtures thereof
(A)
In a more preferred embodiment, the fluorinated ether compound comprises
1, 1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) and CF2HCF2-
0CH2CH20-CF 2CF 2H.
15 In the present invention, the term "non-fluorinated ether compound" is
intended to denote an ether compound, wherein no fluorine atom is present.
Non-limitative examples of suitable non-fluorinated ether compounds
according to the present invention include, notably, the followings:
-aliphatic, cycloaliphatic or aromatic ether, more particularly, dibutyl ether,
20 dipentyl ether, diisopentyl ether, dimethoxyethane (DME), 1,3-dioxolane (DOL),
tetrahydrofuran (THF), 2-methyltetrahydrofuran, and diphenyl ether;
- glycol ethers, such as ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol
monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol
25 monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol
monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-nbutyl
ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether
(DEGME), ethylene glycol diethyl ether, diethylene glycol diethyl ether
(DEGDEE), tetraethylene glycol dimethyl ether (TEGME), polyethylene glycol
30 dimethyl ether (PEGDME);
- glycol ether esters, such as ethylene glycol methyl ether acetate, ethylene
glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate;
In a preferred embodiment, the non-fluorinated ether compound according
to the present invention comprises dimethoxyethane (DME), 1,3-dioxolane
35 (DOL), dibutyl ether, tetraethylene glycol dimethyl ether (TEGME), diethylene
glycol dimethyl ether (DEGME), diethylene glycol diethyl ether (DEGDEE),
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polyethylene glycol dimethyl ether (PEGDME), 2-methyltetrahydrofuran and
tetrahydrofuran (THF).
In a more preferred embodiment, the non-fluorinated ether compound is a
mixture ofDME and DOL.
5 In a more preferred embodiment, the non-fluorinated ether compound is
DME.
In the present invention, the term "anode-less lithium ion battery" is
intended to denote, in particular, the lithium ion battery which does not include an
anode electro-active material on the anode current collector when the battery is
10 assembled and before the first charge. After the first charge, the anode-less lithium
ion battery comprises either a lithium metal thin layer or a lithium alloy thin layer
on the anode current collector. That is, while the anode-less lithium ion battery has
a negative electrode, the term "anode-less" is used because when manufactured a
distinct anode electro-active material is not present in the lithium ion battery.
15 In the present invention, the term "anode" is intended to denote, in particular,
the electrode of an electrochemical cell, where oxidation occurs during
discharging.
In the present invention, the term "cathode" is intended to denote, in
particular, the electrode of an electrochemical cell, where reduction occurs during
20 discharging.
In the present invention, the nature of the "current collector" depends on
whether the electrode thereby provided is either a cathode or anode. Should the
electrode of the invention be a cathode, the current collector typically comprises,
preferably consists of at least one metal selected from the group consisting of
25 Aluminium (Al), Nickel (Ni), Titanium (Ti), and alloys thereof, preferably Al.
Should the electrode of the invention be an anode, the current collector typically
comprises, preferably consists of at least one metal selected from the group
consisting of Lithium (Li), Sodium (Na), Zinc (Zn), Magnesium (Mg), Copper
(Cu) and alloys thereof, preferably Cu.
30 In the present invention, the term "electro-active material" is intended to
denote an electro-active material that is able to incorporate or insert into its
structure and substantially release therefrom lithium ions during the charging
phase and the discharging phase of a battery.
In the case of forming a cathode for an anode-less lithium ion battery, the
35 cathode electro-active material is not particularly limited. It may comprise a
composite metal chalcogenide of formula LiMQ2, wherein M is at least one metal
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selected from transition metals such as Co, Ni, Fe, Mn, Cr, and V and Q is a
chalcogen such as 0 or S. Among these, it is preferred to use a lithium-based
composite metal oxide of formula LiM02, wherein M is the same as defined above.
Preferred examples thereof may include LiCo02, LiNi02, LiNixCo1-x02 (0 < x <
5 1), and spinel-structured LiMn204. Another preferred examples thereof may
include lithium-nickel-manganese-cobalt-based metal oxide of formula
LiNixMnyCoz02 (x+y+z 1, referred to as NMC), for instance
LiNi113Mn113 Co 113 02, LiNio,6Mno,2 Coo,2 02, and lit hi urn-nickel-cobalt -aluminumbased
metal oxide of formula LiNixCoyAlz02 (x+y+z = 1, referred to as NCA), for
10 instance LiNio,8COo,1sAlo,os02.
As an alternative, still in the case of forming a cathode for an anode-less
lithium ion battery, the cathode electro-active compound may comprise a lithiated
or partially lithiated transition metal oxyanion-based electro-active material of
formula M1M2(J04)fE1-f, wherein M1 is lithium, which may be partially substituted
15 by another alkali metal representing less that 20% of the M1 metals, M2 is a
transition metal at the oxidation level of +2 selected from Fe, Mn, Ni or mixtures
thereof, which may be partially substituted by one or more additional metals at
oxidation levels between + 1 and +5 and representing less than 35% of the M2
metals, including 0, J04 is any oxyanion wherein J is either P, S, V, Si, Nb, Mo or
20 a combination thereof, E is a fluoride, hydroxide or chloride anion, f is the molar
fraction ofthe J04 oxyanion, generally comprised between 0.75 and 1.
The M1M2(J04)fE1-f electro-active material as defined above is preferably
phosphate-based and may have an ordered or modified olivine structure.
More preferably, the cathode electro-active material has formula Li3-xM'yM
25 "2-y(J04)3 wherein O~x~3, O~y~2, M' and M" are the same or different metals, at
least one of which being a transition metal, J04 is preferably P04 which may be
partially substituted with another oxyanion, wherein J is either S, V, Si, Nb, Mo
or a combination thereof Still more preferably, the electro-active material is a
phosphate-based electro-active material of formula Li(FexMnl-x)P04 wherein 0 ~
30 x~ 1, wherein x is preferably 1 (that is to say, lithium iron phosphate of formula
LiFeP04).
In a preferred embodiment, the cathode electro-active material is selected
from the group consisting ofLiMQ2, wherein M is at least one metal selected from
Co, Ni, Fe, Mn, Cr and V and Q is 0 or S; LiNixCo1-x02 (0 < x < 1); spinel-
35 structured LiMn204; lithium-nickel-manganese-cobalt-based metal oxide of
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formula LiNixMnyCoz02 (x+y+z = 1 ), lithium-nickel-cobalt-aluminum-based
metal oxide of formula LiNixCoyAlz02 (x+y+z = 1), and LiFeP04.
In one embodiment, at least one electro-active compound according to the
present invention is loaded onto the cathode current collector to have an areal
5 capacity between 1.0 mAh/cm2 and 10.0 mAh/cm2, preferably between 3.0
mAh/cm2 and 8.0 mAh/cm2 and more preferably between 4.0 mAh/cm2 and 7.0
mAh/cm2.
In the present invention, the expression "thickness of the cathode" is
intended to denote a total combined thickness of the cathode current collector and
10 the cathode electro-active material layer.
In one embodiment, the thickness of the cathode according to the present
invention is between 40 11m and 150 11m, preferably between 50 11m and 120 11m,
and more preferably between 60 11m and 100 !J.m.
In the present invention, the lithium salt is selected from the group consisting
15 of:
a) LiN(S02F)2 (lithium bis(fluorosulfonyl)imide: LiFSI), LiN(CF3S02)2
(lithium bis(trifluoromethanesulfonyl)imide : LiTFSI), LiPF6, LiBF4, LiC104, Li
bis(oxalato)borate (LiBOB), LiCF3S03, LiF, LiCl, LiBr, Lii, LiN(C2FsS02)2,
LiN(CF3S02)(RFS02), wherein RF is C2Fs, C4F9 or CF30CF2CF2, LiAsF6,
20 LiC(CF3S02)3,LhS;
b)
wherein R'F is selected from the group consisting ofF, CF3, CHF2, CH2F,
C2HF4, C2H2F3, C2H3F2, C2Fs, C3F7, C3H2Fs, C3H4F3, C4F9, C4H2F1, C4H4Fs,
25 CsFll, C3FsOCF3, C2F40CF3, C2H2F20CF3 and CF20CF3; and
c) combinations thereof
In a preferred embodiment, the lithium salt is LiFSI.
In one embodiment, a molar concentration (M) of the lithium salt in the
liquid electrolyte composition according to the present invention is from 1 M to 8
30 M, preferably from 1 M to 3 M, and more preferably from 1 M to 2M.
By the term "separator", it is hereby intended to denote a
monolayer or multilayer polymeric, nonwoven cellulouse or ceramic
material/film, which electrically and physically separates the electrodes of
opposite polarities in an electrochemical device and is permeable to ions flowing
35 between them.
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In the present invention, the separator can be any porous substrate
commonly used for a separator in an electrochemical device.
In one embodiment, the separator is a porous polymeric material comprising
at least one material selected from the group consisting of polyester such as
5 polyethylene terephthalate and polybutylene terephthalate, polyphenylene
sulphide, polyacetal, polyamide, polycarbonate, polyimide, polyether sulfone,
polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene,
polyethylene oxide, polyacrylonitrile, polyolefin such as polyethylene
and polypropylene, or mixtures thereof
10 In a particular embodiment, the separator is a porous polymeric material
coated with inorganic nanoparticles, for instance, Si02, Ti02, Ah03, Zr02, etc.
In another particular embodiment, the separator is a porous polymeric
material coated with polyvinylidene difluoride (PVDF).
According to one embodiment, the c) liquid electrolyte composition further
15 comprises at least one additive, in particular a film-forming additive, which
promotes the formation of the solid electrolyte interface (SEI) layer at the anode
surface and/or cathode surface by reacting in advance of the solvents on the
electrode surfaces. The main components of SEI hence comprise the decomposed
products of electrolyte solvents and salts, which include Li2C03, lithium alkyl
20 carbonate, lithium alkyl oxide and other salt moieties such as LiF for LiPF6-based
electrolytes. Usually, the reduction potential of the film-forming additive is higher
than that of the solvent when reaction occurs at the anode surface, and the
oxidation potential of the film-forming additive is lower than that of the solvent
when the reaction occurs at the cathode side.
25 In one embodiment, the film-forming additive according to the present
invention is an ionic liquid.
The term "ionic liquid" as used herein refers to a compound comprising a
positively charged cation and a negatively charged anion, which is in the liquid
state at the temperature of 1 00°C or less under atmospheric pressure. While
30 ordinary liquids such as water are predominantly made of electrically neutral
molecules, ionic liquids are largely made of ions and short-lived ion pairs. As used
herein, the term "ionic liquid" indicates a compound free from solvent.
The term "onium cation" as used herein refers to a positively charged ion
having at least part of its charge localized on at least one non-metal atom such as
35 0, N, S, orP.
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In the present invention, the ionic liquid has a general formula of An-Q1\nJt),
wherein
- An- represents an anion;
- Q1\nJt) represents a cation;
5 -nand 1, independently selected between 1 and 5, represent respectively the
charges of the anion An- and of the cation Q1\nJt).
The cation(s) may be selected, independently of one another, from metal
cations and organic cations. The cation(s) may be mono-charged cations or
polycharged cations.
10 As metal cation, mention may preferably be made of alkali metal cations,
alkaline-earth metal cations and cations of d-block elements.
In the present invention, Q1\nJt) may represent an onium cation. Onium
cations are cations formed by the elements of Groups VB and VIB (as defined by
the old European IUPAC system according to the Periodic Table of the Elements)
15 with three or four hydrocarbon chains. The Group VB comprises theN, P, As, Sb
and Bi atoms. The Group VIB comprises the 0, S, Se, Te and Po atoms. The onium
cation can in particular be a cation formed by an atom selected from the group
consisting of N, P, 0 and S, more preferably N and P, with three or four
hydrocarbon chains.
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The onium cation Q1\nJt) can be selected from:
- heterocyclic onium cations; in particular those selected from the group
consisting of:
- unsaturated cyclic onium cations; in particular those selected from the
5 group consisting of:
- saturated cyclic onium cations; in particular those selected from the group
consisting of:
R
R
R
R
R
R
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; and
-non-cyclic onium cations; in particular those of general formula +L-R' s, in
which L represents an atom selected from the group consisting ofN, P, 0 and S,
more preferably Nand P, s represents the number ofR' groups selected from 2, 3
5 or 4 according to the valence of the element L, each R' independently represents
a hydrogen atom or a C1 to Cs alkyl group, and the bond between L + and R' can
be a single bond or a double bond.
In the above formulas, each "R" symbol represents, independently of one
another, a hydrogen atom or an organic group. Preferably, each "R" symbol can
10 represent, in the above formulas, independently of one another, a hydrogen atom
or a saturated or unsaturated and linear, branched or cyclic C1 to C1s hydrocarbon
group optionally substituted one or more times by a halogen atom, an amino group,
an imino group, an amide group, an ether group, an ester group, a hydroxyl group,
a carboxyl group, a carbamoyl group, a cyano group, a sulfone group or a sulfite
15 group.
The cation Q1\nJlJ can more particularly be selected from ammonium,
phosphonium, pyridinium, pyrrolidinium, pyrazolinium, imidazolium, arsenium,
quaternary phosphonium and quaternary ammonium cations.
The quaternary phosphonium or quaternary ammonium cations can more
20 preferably be selected from tetraalkylammonium or tetraalkylphosphonium
cations, trialkylbenzylammonium or trialkylbenzylphosphonium cations or
tetraarylammonium or tetraarylphosphonium cations, the alkyl groups of which,
either identical or different, represents a linear or branched alkyl chain having from
4 to 12 carbon atoms, preferably from 4 to 6 carbon atoms, and the aryl groups of
25 which, either identical or different, represents a phenyl or naphthyl group.
In a specific embodiment, Q1\nJlJ represents a quaternary phosphonium or
quaternary ammonium cation.
In one preferred embodiment, Q1+(nlll represents a quaternary phosphonium
cation. Non-limiting examples of the quaternary phosphonium cation comprise
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trihexyl(tetradecyl)phosphonium, and a tetraalkylphosphonium cation,
particularly the tetrabutylphosphonium (PBu4) cation.
In another embodiment, Q1\nJt) represents an imidazolium cation. Nonlimiting
examples ofthe imidazolium cation comprise 1,3-dimethylimidazolium,
5 1-( 4-sulfobutyl)-3-methyl imidazolium, 1-allyl-3H-imidazolium, 1-butyl-3-
methylimidazolium, 1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium,
1-octyl-3-methylimidazolium
In another embodiment, Q1\nJt) represents a quaternary ammonium cation
which is selected in particular from the group consisting oftetraethylammonium,
10 tetrapropylammonium, tetrabutylammonium, trimethylbenzylammonium,
methyltributylammonium, N,N-diethyl-N-methyl-N-(2-methoxyethyl)
ammonium, N,N-dimethyl-N-ethyl-N-(3-methoxypropyl) ammonium, N,Ndimethyl-
N-ethyl-N-benzyl ammonium, N, N-dimethyl-N-ethyl-N-phenylethyl
ammonium, N-tributyl-N-methyl ammonium, N-trimethyl-N-butyl ammonium,
15 N-trimethyl-N-hexyl ammonium, N-trimethyl-N-propyl ammonium, and Aliquat
336 (mixture ofmethyltri(Cs to Cw alkyl)ammonium compounds).
In one embodiment, Q1\nJt) represents a piperidinium cation, in particular Nbutyl-
N-methyl piperidinium, N-propyl-N-methyl piperidinium.
In another embodiment, Q1\nJt) represents a pyridinium cation, in particular
20 N-methylpyridinium.
In a more preferred embodiment, Q1\nJt) represents a pyrrolidinium cation.
Among specific pyrrolidinium cations, mention may be made of the following :
Ct-t2alkyl-Ct-t2alkyl-pyrrolidinium, and more preferably Ct-4alkyl-Ct-4alkylpyrrolidinium.
Examples of pyrrolidinium cations comprise, but not limited to,
25 N,N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, N-isopropyl-Nmethylpyrrolidinium,
N-methyl-N-propylpyrrolidinium, N-butyl-Nmethylpyrrolidinium,
N-octyl-N-methylpyrrolidinium, N-benzyl-Nmethylpyrrolidinium,
N-cyclohexylmethyl-N-methylpyrrolidinium, N-[(2-
hydroxy)ethyl]-N-methylpyrrolidinium. More preferred are N-methyl-N-
30 propylpyrrolidinium (PYR13) and N-butyl-N-methylpyrrolidinium (PYR14).
Non-limiting examples of an anion of the ionic liquid comprise iodide,
bromide, chloride, hydrogen sulfate, dicyanamide, acetate, diethyl phosphate,
methyl phosphonate, fluorinated amon, e.g.,
hexafluorophosphate (PF6-) and tetrafluoroborate
(BF4t and oxalatooborate ofthe following formula:
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In one embodiment, An-is a fluorinated anion. Among the fluorinated anions
5 that can be used in the present invention, fluorinated sulfonimide anions may be
particularly advantageous. The organic anion may, in particular, be selected from
the anions having the following general formula:
(Ea-S02)N- R
in which:
10 - Ea represents a fluorine atom or a group having preferably from 1 to 10
carbon atoms, selected from fluoroalkyls, perfluoroalkyls and fluoroalkenyls, and
- R represents a substituent.
Preferably, Ea may represent For CF3.
According to a first embodiment, R represents a hydrogen atom.
15 According to a second embodiment, R represents a linear or branched, cyclic
or non-cyclic hydrocarbon-based group, preferably having from 1 to 10 carbon
atoms, which can optionally bear one or more unsaturations, and which is
optionally substituted one or more times with a halogen atom, a nitrile function,
or an alkyl group optionally substituted one of several times by a halogen atom.
20 Moreover, R may represent a nitrile group -CN.
According to a third embodiment, R represents a sulfinate group. In
particular, R may represent the group -S02-Ea, Ea being as defined above. In this
case, the fluorinated anion may be symmetrical, i.e. such that the two Ea groups of
the anion are identical, or non-symmetrical, i.e. such that the two Ea groups of the
25 anion are different.
Moreover, R may represent the group -S02-R', R' representing a linear or
branched, cyclic or non-cyclic hydrocarbon-based group, preferably having from
1 to 10 carbon atoms, which can optionally bear one or more unsaturations, and
which is optionally substituted one or more times with a halogen atom, a nitrile
30 function, or an alkyl group optionally substituted one of several times by a halogen
atom. In particular, R' may comprise a vinyl or allyl group. Furthermore, R may
represent the group -S02-N-R', R' being as defined above or else R' represents a
sulfonate function -S03.
Cyclic hydrocarbon-based groups may preferably refer to a cycloalkyl group
3 5 or to an aryl group. "Cycloalkyl" refers to a monocyclic hydrocarbon chain, having
3 to 8 carbon atoms. Preferred examples of cycloalkyl groups are cyclopentyl and
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cyclohexyl. "Aryl" refers to a monocyclic or polycyclic aromatic hydrocarbon
group, having 6 to 20 carbon atoms. Preferred examples of aryl groups are phenyl
and naphthyl. When a group is a polycyclic group, the rings may be condensed or
attached by cr (sigma) bonds.
5 According to a fourth embodiment, R represents a carbonyl group. R may,
in particular, be represented by the formula -CO-R', R' being as defined above.
The organic anion that can be used in the present invention may
advantageously be selected from the group consisting of CF3S02N-S02CF3
(bis(trifluoromethane sulfonyl)imide anion, commonly denoted as TFSI), FS02N-
10 S02F (bis(fluorosulfonyl)imide anion, commonly denoted as FSI), CF3S02NS02F,
and CF3S02N-S02N-S02CF3.
In a preferred embodiment, the ionic liquid contains:
- a positively charged cation selected from the group consisting of
imidazolnium, pyridinium, pyrrolidinium and piperidinium ions optionally
15 containing one or more C1-C3o alkyl groups, and
- a negatively charged anion selected from the group consisting of halides,
fluorinated anions, and borates.
Non-limiting examples of C1-C3o alkyl groups include, notably, methyl,
ethyl, propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl,
20 2,2-dimethyl-propyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pentyl,
2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl and dodecyl
groups.
In one preferred embodiment, the film-forming additive according to the
present invention is selected from the group consisting of N-methyl-N-
25 propylpyrrolidinium bis(fluorosulfonyl) imide (PYR13FSI), N-butyl-Nmethylpyrrolidinium
bis(fluorosulfonyl) imide (PYR14FSI), N-methyl-Npropylpyrrolidinium
bis(trifluoromethanesulfonyl) imide (PYR13TFSI), and Nbutyl-
N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR14TFSI).
In another embodiment, the film-forming additive according to the present
30 invention is selected from the group consisting of cyclic sulfite and sulfate
compounds comprising 1,3-propanesultone (PS), ethylene sulfite (ES) and prop-
1-ene-1,3-sultone (PES); sulfone derivatives comprising dimethyl sulfone,
tetramethylene sulfone (also known as sulfolane), ethyl methyl sulfone and
isopropyl methyl sulfone; nitrile derivatives comprising succinonitrile,
35 adiponitrile, and glutaronitrile; lithium nitrate (LiN03); boron derivatives salt
comprising lithium difluoro oxalato borate (LiDFOB), lithium fluoromalonato
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(difluoro)borate (LiFMDFB), vinyl acetate, biphenyl benzene, isopropyl benzene,
hexafluorobenzene, tris(trimethylsilyl)phosphate, triphenyl phosphine, ethyl
diphenylphosphinite, triethyl phosphite, tris(2,2,2-trifluoroethyl) phosphite,
maleic anhydride, vinylene carbonate, vinyl ethylene carbonate, mono-fluorinated
5 ethylene carbonate (4-fluoro-1,3-dioxolan-2-one), difluorinated ethylene
carbonate, cesium bis(trifluorosulfonyl)imide (CsTFSI) and cesium fluoride
(CsF), and mixtures thereof
In one preferred embodiment, the film-forming additive according to the
present invention is vinylene carbonate.
10 In the present invention, the total amount of the film-forming additive(s)
may be from 0 to 30 wt%, preferably from 0 to 20 wt%, more preferably from 0
to 15 wt%, and even more preferably from 0 to 5 wt% with respect to the total
weight ofb) the liquid electrolyte solution.
The total amount of the film-forming additive(s), if contained in the liquid
15 electrolyte solution of the present invention, may be from 0.05 to 10.0 wt%,
preferably from 0.05 to 5.0 wt%, and more preferably from 0.05 to 2.0 wt% with
respect to the total weight ofb) the liquid electrolyte solution.
In a preferred embodiment, the total amount of film-forming additive(s)
accounts for at least 1.0 wt% ofb) the liquid electrolyte solution.
20 Should the disclosure of any patents, patent applications, and publications
which are incorporated herein by reference conflict with the description of the
present application to the extent that it may render a term unclear, the present
description shall take precedence.
The invention will be now explained in more detail with reference to the
25 following examples, whose purpose is merely illustrative and not intended to limit
the scope of the invention.
EXAMPLES
Raw Materials
30 Dry cell: NCM523/Cu (current collector; 15 11m)/CCS (ceramic coated
35
separator), commercially available from Lifun Technology (Model No.: 402035)
Fluorinated ether compounds:
1, 1 ,2,2-tetrafluoroethy 1-2,2, 3, 3 -tetrafl uoropropy 1 ether (TTE),
commercially available from SynQuest
CF2HCF2-0CH2CH20-CF2CF2H (C6FsH602), synthesized within
Solvay
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difluoroethyl acetate (DFEA) available from Solvay
Methyl 2,2,2-trifluoroethyl carbonate (F3EMC) available from Solvay
Non-fluorinated ether compound:
1,2-dimethoxyethane (DME), commercially available from Enchem
5 Other solvents
10
fluoroethylene carbonate (FEC), commercially available from Enchem
ethylene carbonate (EC), commercially available from Enchem
ethyl methyl carbonate (EMC), commercially available from Enchem
Li salt: lithium bis(fluorosulfonyl)imide (LiFSI), commercially
available from Nippon Shokubai
AI Formulation of the electrolyte compositions:
The electrolyte compositions were prepared for the Inventive Examples of
E1-E2 and Comparative Examples of CE1-CE4. Their constituents are
15 summarized in Table 1 below:
Table 1
Examples Solvent mixture Li Salt
DME/TTE 1M LiFSI
E1
(20/80)*(91.94)** (8.06)**
E2 DME/C6FsH602 1M LiFSI
(20/80)*(91.94)** (8.06)**
CE1 DME 1M LiFSI
(100)*(91.94)** (8.06)**
CE2 DME/DFEA 1M LiFSI
(20/80)*(91.94)** (8.06)**
CE3 FEC/F3EMC 1M LiFSI
(20/80)*(91.94)** (8.06)**
CE4 FEC/EMC 1M LiFSI
(20/80)*(91.94)** (8.06)**
* : vol% with respect to the total volume of the solvent mixture
** : vol% with respect to the total volume of the liquid electrolyte composition
When preparing the electrolyte composition of E1, 1M LiFSI was first
20 dissolved in 20 vol% of DME with respect to the total volume of the solvent
mixture and was mixed using a magnetic stirrer within a glove box. After the
solution became transparent, 80 vol% of TTE was added to the solution with
respect to the total volume of the solvent mixture.
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The electrolyte compositions of E2 were prepared in the same manner as
E 1, except C6F sH602 was used as a fluorinated ether compound instead of TTE.
The solvent mixture for E1-E2 comprised 20 vol% of DME and 80 vol% of a
fluorinated ether compound, respectively, with respect to the total volume of the
5 solvent mixture.
When preparing the electrolyte composition of CE1, 1M LiFSI was
dissolved in DME using a magnetic stirrer within a glove box.
When preparing the electrolyte composition of CE2, 1M LiFSI was first
dissolved in 20 vol% of DME with respect to the total volume of the solvent
10 mixture and was mixed using a magnetic stirrer within a glove box. After the
solution became transparent, 80 vol% of DFEA was added to the solution with
respect to the total volume of the solvent mixture.
When preparing the electrolyte composition of CE3, all the required
compounds were added to one bottle and they were mixed until a transparent
15 solution was obtained. 1M LiFSI was dissolved in a solvent mixture of 20 vol%
ofFEC and 80 vol% ofF3EMC for CE3.
20
The electrolyte composition of CE4 was prepared by dissolving 20 vol%
ofFEC within 80 vol% ofEMC first with respect to the total volume of the solvent
mixture, and then 1M LiFSI was dissolved in said solvent mixture.
B/ Preparation of the anode-less cells:
1-Drying and Electrolyte Injection
The NCM523/Cu dry cell without electrolyte from Lifun Technology was
dried under vacuum at 55°C for 2 days. The electrolyte composition as prepared
25 was injected to the dry cell by pipetting (4.0 g/Ah). After injection, the dry cell
was left under vacuum and the cell pressure released right after the vacuum. There
were 3 times of vacuum-releasing process to wet the cathode materials After
releasing the vacuum, the cell was left for additional 1 hour for sufficient wetting.
2-Sealing and 1st Aging
30 After wetting, the cell was sealed by using a vacuum sealing machine under
the pressure (up to 350 kPa), wherein the cell was sandwiched with two plates
having screwing tools. Subsequently, the cell was left at room temperature for 1
day (1st aging).
3 5 C/ Activation of cells and Measurement of initial cell performance
1-2nd Aging (=Activation/Formation ofthe anode-free cell)
5
10
15
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The cell was charged to a 30% level of State Of Charge (SOC) for 3 hours
and then was left at 45°C for another 1 day (2nd aging).
2-Degassing
The gas generated during the activation of the anode-free cell was removed
by opening the cell and re-sealing the same.
D/ Performance Measurement of the anode-less cells
The anode-free cells were tested at various conditions as detailed below:
!-Capacity check for 3 cycles
o Charging: 0.1C/4.2V/0.05C at constant current and constant
voltage (CC-CV)
o Discharging: 0.1C/3.6V (CC)
2-Continuous cycling test (up to 200 cycles)
o Charging: 0.2C/4.2V/0.05C (CC-CV)
o Discharging: 0.5C/3.6V (CC)
E/ Cycle tests - Capacity retention:
The cycling ability of each cell was evaluated. Then, each cell was subjected
to a repetition of cycles of charge and discharge. One cycle consisted of a charging
phase at a charging current of C followed by a discharge phase at a discharge
20 current of C. The following results were obtained as shown in Table 2 below:
25
Table 2
Examples
Number of cycles
at 80% of capacity retention
El 150
E2 196
CEI Short-circuit
CE2 Short-circuit
CE3 23
CE4 19
Figures 1-2 show the variation of the capacity retention and the Coulombic
efficiency ofEl-E2 and CE1-CE4 as a function of the cycle number.
Notably, it was observed that the discharged capacity of El-E2, all
according to the present invention, decreased slowly as the number of cycles
increased (Figure 1 ). In particular, Figure 2 clearly shows that the number of cycles
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at 80% of capacity retention for Inventive Examples, i.e., E1-E2, each comprising
the electrolyte composition according to the invention, were much higher than
those for Comparative Examples, i.e., CE1-CE4.
Among Inventive Examples of E1-E2, the number of cycles at 80% of
5 capacity retention ofE1 was the lowest, i.e., 150 cycles. However, such lowest
number ofE1 was already much higher than the number of cycles of Comparative
Examples ofCE1-CE4. The highest number of cycles at 80% of capacity retention
among CE1-CE4 was 23 cycles from CE3, while CE1 and CE2 resulted in almost
immediate short-circuits. It was hence clearly demonstrated that the cycling ability
10 was improved according to the present invention.
Further, one can note that the Coulombic efficiency oflnventive Examples
E1-E2 shown in Figure 2 remained essentially constant up to at least 150 cycles
and decreased as the cycles further increased, but very slowly, whereas the
Coulombic efficiency of Comparative Examples CE1-CE4 decreased rapidly
15 around 10~20 cycles.

CLAIMS
1. An anode-less lithium ion battery comprising:
a) a cathode comprising a cathode current collector and a cathode electroactive
material on the cathode current collector;
5 b) an anode current collector;
c) a liquid electrolyte composition between the a) cathode and the b) anode
current collector; and
d) a separator,
wherein the c) liquid electrolyte composition comprises i) at least 70% by
10 volume (vol%) of a solvent mixture with respect to the total volume ofthe
electrolyte composition, comprising at least one fluorinated ether compound and
at least one non-fluorinated ether compound, and ii) at least one lithium salt.
2. The anode-less lithium ion battery according to claim 1, wherein the
solvent mixture comprises
15 - from 60 to 90 vol% of at least one fluorinated ether compound; and
-from 10 to 40 vol% of at least one non-fluorinated ether compound, with
respect to the total volume of the solvent mixture.
3. The anode-less lithium ion battery according to claim 1 or 2, wherein
the solvent mixture comprises
20 - from 80 to 90 vol% of at least one fluorinated ether compound; and
-from 10 to 20 vol% of at least one non-fluorinated ether compound, with
respect to the total volume of the solvent mixture.
4. The anode-less lithium ion battery according to any of claims 1 to 3,
wherein the fluorinated ether compound has a chemical formula of CaFbHcOct,
25 wherein a,b,c and dare all integers, dis an integer from 1 to 3, a is an integer
from 3 to 10, preferably from 4 to 7, and 2*(a+ 1) = b+c.
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5. The anode-less lithium ion battery according to any of claims 1 to 4,
wherein the fluorinated ether compound comprises 1, 1,2,2-tetrafluoroethyl-
2,2,3,3-tetrafluoropropyl ether (TTE) and CF2HCF2-0CH2CH20-CF2CF2H.
6. The anode-less lithium ion battery according to any of claims 1 to 5,
5 wherein the non-fluorinated ether compound comprises dimethoxyethane
(DME), 1,3-dioxolane (DOL), dibutyl ether, tetraethylene glycol dimethyl ether
(TEGME), diethylene glycol dimethyl ether (DEGME), diethylene glycol diethyl
ether (DEGDEE), polyethylene glycol dimethyl ether (PEGDME), 2-
methyltetrahydrofuran and tetrahydrofuran (THF).
10 7. The anode-less lithium ion battery according to any of claims 1 to 6,
wherein the cathode electro-active material is selected from the group consisting
ofLiMQ2, wherein M is at least one metal selected from Co, Ni, Fe, Mn, Cr and
V and Q is 0 or S; LiNixCo1-x02 (0 < x < 1); spinel-structured LiMn204; lithiumnickel-
manganese-cobalt-based metal oxide of formula LiNixMnyCoz02 (x+y+z
15 = 1), lithium-nickel-cobalt-aluminum-based metal oxide offormula
LiNixCoyAlz02 (x+y+z = 1), and LiFeP04.
8. The anode-less lithium ion battery according to any of claims 1 to 7,
wherein the cathode electro-active material is loaded onto the cathode current
collector to have an areal capacity between 1.0 mAh/cm2 and 10.0 mAh/cm2,
20 preferably between 3.0 mAh/cm2 and 8.0 mAh/cm2 and more preferably between
4.0 mAh/cm2 and 7.0 mAh/cm2.
9. The anode-less lithium ion battery according to any of claims 1 to 8,
wherein the lithium salt is selected from the group consisting of:
a) LiN(S02F)2 (lithium bis(fluorosulfonyl)imide: LiFSI), LiN(CF3S02)2
25 (lithium bis(trifluoromethanesulfonyl)imide : LiTFSI), LiPF6, LiBF4, LiC104, Li
bis(oxalato)borate (LiBOB), LiCF3S03, LiF, LiCl, LiBr, Lil, LiN(C2FsS02)2,
LiN(CF3S02)(RFS02), wherein RF is C2Fs, C4F9 or CF30CF2CF2, LiAsF6,
LiC(CF3S02)3, LhS;
b)
30
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wherein R'F is selected from the group consisting ofF, CF3, CHF2, CH2F,
C2HF4, C2H2F3, C2H3F2, C2Fs, C3F7, C3H2Fs, C3H4F3, C4F9, C4H2F1, C4H4Fs,
CsFll, C3FsOCF3, C2F40CF3, C2H2F20CF3 and CF20CF3; and
c) combinations thereof
5 10. The anode-less lithium ion battery according to any of claims 1 to 9,
wherein a concentration of the lithium salt is from 1 M to 8 M, preferably from 1
M to 3 M, and more preferably 1 M to 2 M.
11. The anode-less lithium ion battery according to any of claims 1 to 10,
wherein the d) separator is a porous polymeric material comprising at least one
10 material selected from the group consisting of polyester such as polyethylene
terephthalate and polybutylene terephthalate, polyphenylene sulphide,
polyacetal, polyamide, polycarbonate, polyimide, polyether sulfone,
polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene,
polyethylene oxide, polyacrylonitrile, polyolefin such as polyethylene
15 and polypropylene, or mixtures thereof
12. The anode-less lithium ion battery according to any of claims 1 to 11,
further comprising from 0.05 to 10.0 wt% of at least one film-forming additive,
preferably from 0.05 to 5.0 wt% of at least one film-forming additive and more
preferably from 0.05 to 2.0 wt% of at least one film-forming additive with
20 respect to the total weight of the liquid electrolyte composition.
13. The anode-less lithium ion battery according to claim 12, wherein the
film-forming additive is selected from the group consisting of cyclic sulphite and
sulfate compounds comprising 1,3-propanesultone (PS), ethylene sulphite (ES)
and prop-1-ene-1,3-sultone (PES); sulfone derivatives comprising dimethyl
25 sulfone, tetramethylene sulfone (also known as sulfolane), ethyl methyl sulfone
and isopropyl methyl sulfone; nitrile derivatives comprising succinonitrile,
adiponitrile, and glutaronitirle; and lithium nitrate (LiN03); boron derivatives
salt comprising lithium difluoro oxalato borate (LiDFOB), lithium
fluoromalonato (difluoro)borate (LiFMDFB), vinyl acetate, biphenyl benzene,
30 isopropyl benzene, hexafluorobenzene, tris(trimethylsilyl)phosphate, triphenyl
phosphine, ethyl diphenylphosphinite, triethyl phosphite, tris(2,2,2-
trifluoroethyl) phosphite, maleic anhydride, vinylene carbonate, vinyl ethylene
carbonate, mono-fluorinated ethylene carbonate ( 4- fluoro-1 ,3-dioxolan-2-one ),
wo 2021/213743 PCT/EP2021/056900
- 28-
difluorinated ethylene carbonate, cesium bis(triflulorosulfonyl)imide (CsTFSI),
cesium fluoride (CsF), and mixtures thereof
14. The anode-less lithium ion battery according to claim 12, wherein the
film-forming additive is an ionic liquid.
5 15. The anode-less lithium ion battery according to claim 14, wherein the
ionic liquid is selected from the group consisting ofN-methyl-Npropylpyrrolidinium
bis(fluorosulfonyl) imide (PYR13FSI), N-butyl-Nmethylpyrrolidinium
bis(fluorosulfonyl) imide (PYR14FSI), N-methyl-Npropylpyrrolidinium
bis(trifluoromethanesulfonyl) imide (PYR13TFSI), and N-
10 butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR14TFSI).