DE102015014294A1 - Electrolytic composition for reduced gas formation in wide temperature range cycles - Google Patents

Abstract

A rechargeable battery cell is proposed which has a special combination of anode, cathode and electrolyte composition. The electrolyte composition includes an additive system and a salt system. The additive system includes a first sulfonyl group-containing additive, an anti-gassing agent and a second additive. The salt system includes a lithium salt and a co-salt. The disclosed electrolyte composition reduces gas formation and improves performance over a wide temperature range.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of International Patent Application PCT / US2013 / 045513 entitled "Nonaqueous Electrolytic Rechargeable Batteries for Operation in Extended Temperature Range", filed June 12, 2013, which is the priority of U.S. Provisional Application No. 5,256,259. No. 61 / 658,712, entitled "Microhybrid Battery", filed Jun. 12, 2012, and the priority of US Provisional Application No. 61 / 658,704 entitled "Nonaqueous Electrolyte Lithium Ion Cell Containing a Solvent Binding "filed 12 June 2012, the entire contents of which are hereby incorporated by reference in their entirety for all purposes.

TECHNICAL AREA

This invention relates to an electrolyte composition comprising at least a first additive containing a sulfonyl group, a specific salt system, and an anti-gassing additive within certain ratios for use in a rechargeable battery.

BACKGROUND AND ABSTRACT

Rechargeable batteries produce energy from electrochemical reactions. In typical rechargeable batteries, the battery is designed to provide optimum performance at or near room temperature. Extremely high or low temperatures may affect the performance and / or life of the battery. To address the performance issues of extreme temperatures, batteries can integrate heating and / or cooling systems that increase volume, weight, complexity and cost. In many cases, this can limit the use of batteries for extreme temperature applications.

More recently, batteries have been developed with cells having a particular combination of anode, cathode, and electrolyte compositions to maintain a long service life at high temperatures while providing energy at low temperatures. For example Cho, in WO 2013/188594 , which is hereby incorporated by reference for all purposes, discloses an electrolyte composition for use in rechargeable batteries comprising a first sulfonyl group-containing additive. As disclosed by Cho, the use of sulfonyl group-containing additives in the electrolyte can provide a battery that maintains cycle life at high temperatures and supplies energy at low temperatures, thereby significantly reducing the requirement for thermal management systems.

Cho discloses in particular a rechargeable battery, comprising a non-aqueous electrolyte solution comprising a lithium salt LiPF ₆ in 0.6-2 M and an organic solvent mixture containing 35 vol .-% ethylene, 5 vol .-% of propylene carbonate, 50 volume % Ethyl methyl carbonate and 10% by volume diethyl carbonate and at least one additive containing a sulfonyl group, ethylene sulfite at 0.1-5% by weight and vinylene carbonate at 0.2-8% by volume. includes. Cho's proposed electrolyte composition provides a performance boost for cold starting an engine compared to acid batteries and maintains a long service life at high temperatures.

The use of the additive containing the sulfonyl groups in addition to the vinylene carbonate in organic electrolyte provides a stable, lower-resistance rechargeable lithium-ion battery. The additive containing the sulfonyl group can lower the impedance by reacting with the anode to provide a stable, solid electrolyte interface (SEI) that is more ionically conductive than an electrolyte without the additive. Moreover, the vinylene carbonate can be efficient in passivating the carbon-based anode during the initial charging, making the SEI less soluble, and thus decomposition of the sulfonyl additive can be reduced.

However, the inventors have recognized that an improved electrolyte composition based on the electrolyte disclosed by Cho can be provided to improve performance at extreme temperatures and to reduce gas formation. There is provided an electrolyte composition comprising a first additive containing a sulfonyl group, an anti-gassing agent, a second additive, and a salt system. Furthermore, the electrolyte composition comprises vinylene carbonate and a solvent system. The electrolyte composition may be used in various cell constructions, but may be particularly advantageous in a pouch design due to reduced gas formation.

The disclosed electrolyte composition can reduce gas formation over a wide temperature range during the cycle. Further, the ratio between the sulfonyl group additive and vinylene carbonate can be controlled to provide an improved SEI layer for improved cell cycle efficiency. As provided herein, the optimized electrolyte composition reduces / maintains impedance and provides improved performance during cold start, and also reduces gas formation during high temperature cycling and / or storage.

As indicated herein, the first additive containing a sulfonyl group may correspond to 0.1 to 5 weight percent of the electrolyte composition. The anti-gassing agent may be equal to or less than 2% by weight while the second additive is 0.1-5% by weight of the electrolyte composition. The additional additive can be selected to reduce the level of vinylene carbonate while maintaining good SEI performance. The salt system may comprise a lithium salt in combination with a co-salt, and it is unlikely for the co-salt to produce Lewis acid decomposition.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined solely by the claims which follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

1 illustrates the initial capacity loss of the electrolyte composition in an LFP / graphite cell as compared to control electrolyte.

2 Figure 12 illustrates the initial capacity loss of the electrolyte composition in a cell comprising an NCM cathode and a graphite anode as compared to control electrolyte.

3 illustrates the impedance of the electrolyte composition in an LFP / Graphite cell as compared to control electrolyte.

4 Figure 12 shows the impedance of the electrolyte composition in an NCM / graphite cell compared to control electrolyte.

5A Figure 3 shows the hybrid pulse performance (HPPC) at 23 ° C of the electrolyte composition in an LFP / Graphite cell at 1 second pulse power as compared to control electrolyte.

5B illustrates the hybrid pulse performance (HPPC) at 23 ° C of the electrolyte composition in an LFP / graphite cell at 10 seconds pulse power compared to control electrolyte.

6A illustrates the hybrid pulse performance (HPPC) at -20 ° C of the electrolyte composition in an LFP / Graphite cell at 1 second pulse power compared to control electrolyte.

6B illustrates the hybrid pulse performance (HPPC) at -20 ° C of the electrolyte composition in an LFP / Graphite cell at 10 second pulse power compared to control electrolyte.

7 Figure 12 illustrates the performance resulting from a cold start test at -30 ° C with the electrolyte composition in LFP / graphite cells as compared to control electrolyte.

8th illustrates the performance resulting from a cold-start test at -30 ° C for NCM / graphite cells with the electrolyte composition as compared to control electrolyte.

9 Figure 11 shows the high temperature life test results for NCM / graphite cells with the electrolyte composition compared to control electrolyte.

10 shows the change in volume during a 55 ° C storage of LFP / graphite cells with the electrolyte composition compared to control electrolyte.

11 shows an exemplary bag construction for use with the electrolyte composition.

DETAILED DESCRIPTION

Aspects of this disclosure will now be described by way of example and with reference to the illustrated embodiments listed above. Components, process steps and other elements that are substantially the same in one or more embodiments are identified in a coordinated fashion and described with minimal repetition. However, it should be noted that elements that have been identified in a coordinated manner may also differ to some extent.

This disclosure provides an optimized electrolyte composition comprising a first additive containing a sulfonyl group, an anti-gassing agent, a second additive to reduce impedance, and a salt system. This optimized electrolyte composition provides an unexpected improvement in initial capacity loss, illustrated in US Pat 1 and 2 , compared to control electrolyte compositions. Furthermore, the optimized electrolyte composition gives similar and / or reduced DC and AC resistances (DCR, ACR), as in US Pat 3 . 4 . 5A . 5B . 6A and 6B shown compared to control electrolyte compositions. The optimized electrolyte composition also exhibits improved cold-start performance, illustrated in U.S. Pat 7 and 8th , and unexpected improvements in cycling over a wide temperature range, presented in 9 , In addition, the specific electrolyte composition has an unexpected result of reducing impedance while reducing gas formation, illustrated in FIG 10 , The low gas formation of the electrolyte composition allows the use of the electrolyte composition in various cell constructions, particularly a bag construction, illustrated in US Pat 11 ,

As described above, the electrolyte composition results in low gas formation at high temperatures, with still low impedance at very low temperatures, and provides good SEI development. Shown in Table 1 are the ranges of additives and salt system of an example of an electrolyte composition according to the present invention. Table 1: Electrolyte composition AREA additive system First additive containing a sulfonyl group 0.1 to 5% by weight vinylene 0.1 to 5% by weight Anti-gas formation additive less than 2% by weight Second additive 0.1 to 5% by weight salt system Litiumsalz 0.1 to 2.0 M Co salt 0.05 to 0.25 M

As shown in the above table, the electrolyte composition may include an additive system and a salt system. The additive system contains components each in less than 5 wt. The disclosed additive system comprises a first additive containing a sulfonyl group, vinylene carbonate, an anti-gassing additive, and a second additive. The combination of the first additive containing a sulfonyl group, the vinylene carbonate, the anti-gassing additive and the second additive reduce the impedance and reinforce the SEI layer.

Further, the anti-gasification additive in the disclosed additive system reduces gas generation that may result from reactions of one or more of the other additives, such as the first additive containing a sulfonyl group. The electrolyte additive system is specifically designed to control gas generation and reduce the impedance increase of some additives, such as increased impedance of the anti-gasification and SEI-forming additives, by providing a composition containing a lower weight fraction of the additive containing a sulfonyl group a lower weight fraction of the SEI-forming additive may be used in combination with a salt system.

The disclosed salt system allows a smaller amount of LiPF ₆ to be used, since a Co salt is included. The Co salt is selected from a group that does not generate Lewis acidic species during decomposition. The inclusion of the Co salt has the unexpected effect of allowing the use of a minor weight fraction of the at least one additive containing a sulfonyl group due to the lower concentration of Lewis acidic products from the decomposition of LiPF ₆ . The lower weight fraction of the at least one additive containing a sulfonyl group also has the unexpected advantage that a smaller amount of an anti-gassing agent is possible to reduce the high impedance effect generally encountered with anti-gassing agents. This unique formulation results in a cell with low gas formation and reduced impedance, in contrast to the use of anti-gasification additives combined with additives containing sulfonyl groups.

In use, the electrolyte composition provides an improved battery. For example, a rechargeable battery that includes an anode (also referred to as a negative electrode), a cathode (also referred to as a positive electrode), a separator, and a non-aqueous electrolyte solution, such as the electrolyte of the present disclosure. The rechargeable batteries disclosed herein are low-gassing, have long life over a wide temperature range, reduce impedance, and improve performance during cold start. As another example, the electrolyte composition may be used in a lithium-ion battery.

As described above, the electrolyte composition is a non-aqueous electrolyte solution and may include an additive system and a salt system. The additive system may include a first additive containing a sulfonyl group, vinylene carbonate, an anti-gassing additive and a second additive. In one example, the salt system may contain LiPF ₆ and a Co salt. Furthermore, the solution contains a solvent system.

undThe at least one first additive containing a sulfonyl group can reduce the charge of the vinylene carbonate while maintaining good SEI development. For example, the first additive containing a sulfonyl group can be represented by the formula (1): R ₁ -AR ₂ (1) wherein R ₁ and R ₂ independently represent an alkyl group which may be substituted with an aryl group or a halogen atom; an aryl group may be substituted with an alkyl group or a halogen atom; or taken together to form, together with -A-, a cyclic structure which may further contain an unsaturated bond, wherein "A" is represented by a formula selected from the group comprising:

and

R ₁ or R ₂ may be an alkyl group having 1 to 4 carbon atoms, which may be exemplified specifically as a methyl group, ethyl group, propyl group, isopropyl group and butyl group. Examples of an aryl group which can substitute the alkyl group include a phenyl group, naphthyl group and anthranyl group, among them, the phenyl group is preferable. Examples of a halogen atom which can substitute the alkyl group include fluorine, chlorine and bromine. A plurality of these substituents can replace the alkyl group, and simultaneous substitution by an aryl group and halogen group is also permissible.

The cyclic structure formed by R ₁ and R ₂ with each other and together with -Abunden is of the kind of a four-membered or larger ring and may contain a double bond or triple bond. Examples of bound group formed by the bound together R1 and R2 include CH ₂ -, --CH ₂ CH ₂ CH ₂ -, --CH ₂ CH ₂ CH ₂ CH ₂ -, --CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, --CH = CH--, --CH = CHCH ₂ -, --CH ₂ CH = CHCH ₂ -, and --H ₂ H ₂ ≡CCH ₂ CH ₂ - one. One or more hydrogen atoms in these groups may be replaced by alkyl group (s), halogen atom (s), aryl group (s) and so on.

Specific examples of the molecule having "A" as represented by the formula (2) include linear sulfites. For example, dimethyl sulfite, diethyl sulfite, ethyl methyl sulfite, methyl propyl sulfite, ethyl propyl sulfite, diphenyl sulfite, methyl phenyl sulfite, ethyl sulfite, dibenzyl sulfite, benzyl methyl sulfite and benzyl ethyl sulfite; cyclic sulfites such as ethylene sulfite, propylene sulfite, butylene sulfite, vinylene sulfite, phenylethylene sulfite, 1-methyl-2-phenyl ethylene sulfite and 1-ethyl-2-phenyl ethylene sulfite; and halides of such linear and cyclic sulfites.

Specific examples of the molecule having "A" as represented by the formula (3) include linear sulfones such as dimethylsulfone, diethylsulfone, ethylmethylsulfone, methylpropylsulfone, ethylpropylsulfone, diphenylsulfone, methylphenylsulfone, ethylphenylsulfone dibenzylsulfone, benzylmethylsulfone and benzyl ethyl sulfone: cyclic sulfones such as sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-ethyl sulfolane, 3-ethyl sulfolane, 2,4-dimethyl sulfolane, sulfolene, 3-methyl sulfolene, 2-phenyl sulfolane and 3- phenyl sulfolane; and halides of such linear and cyclic sulfones.

Specific examples of the molecule having "A" as represented by the formula (A) include linear sulfonic acid esters such as methyl methane sulfonate, ethyl methane sulfonate, propyl methane sulfonate, methyl ethane sulfonate, ethyl ethane sulfonate, propyl ethane sulfonate, methyl benzene sulfonate, ethyl benzene sulfonate, propyl benzenesulfonate phenyl Methanesulfonate, ethanesulfonate-phenyl, phenyl-propanesulfonate, methyl-benzylsulfonate, ethyl-benzylsulfonate, propyl-benzylsulfonate, benzyl-methanesulfonate, benzyl-ethanesulfonate and benzyl-propanesulfonate; cyclic sulfonic acid esters such as 1,3-propanesultone, 1,4-butanesultone, 3-phenyl-1,3-propanesultone and 4-phenyl-1,4-butanesultone; and halides of such linear and cyclic sulfonic acid esters.

Specific examples of the molecule having "A" as represented by the formula (5) include chain sulfuric acid esters such as dimethyl sulfate, diethyl sulfate, ethyl methyl sulfate, methyl propyl sulfate, ethyl propyl ether sulfate, methyl phenyl sulfate, ethyl phenyl sulfate , Phenylpropyl sulfate, benzylmethylsulfate and benzyl-ethylsulfate; cyclic sulfuric acid esters such as ethylene glycol-sulfuric acid ester, 1,2-propanediol, sulfuric acid ester, 1,3-propanediol-sulfuric acid ester, 1,2-butanediol-sulfuric acid ester, 1,3-butanediol-sulfuric acid ester, 2,3-butanediol-sulfuric acid ester, phenylethylene glycol Sulfuric acid ester, methylphenylethylene glycol sulfuric acid ester and ethylphenylethylene glycol sulfuric acid ester; and halides of such chain and cyclic sulfuric acid esters.

The molecule represented by the formula (1) may be used singly or two or more of such molecules may be used in combination in the electrolyte composition.

The first additive containing a sulfonyl group represented by the formula (1) is exemplified as ethylene sulfite, dimethyl sulfite, sulfolane, sulfolene and sultone.

The amount of the first additive represented by the formula (1) contained in the organic solvent of the nonaqueous electrolytic solution is preferably within a range of 0.05 to 100 vol., 0.05 to 60 vol.%, 0.1 to 15 vol.% Or 0.5 to 2 vol.%. Alternatively, the first additive is in a range of 0.1 to 5 wt%, 0.1 to 3 wt%, or 0.1 to 1 wt% of the electrolyte composition. Some of the first additives represented by the formula (1) are solid at room temperature, such molecules are preferably used in an amount equal to or lower than the saturation solubility for the organic solvent, and more preferably at 60% by weight of the saturation solubility or lower and more preferably 30% by weight or lower. Thus, the additive remains dissolved and in solution in the organic solvent over an expected use temperature range, such as between -30 ° C and + 60 ° C.

Vinylene carbonate is efficient in passivating the carbon-based anode during initial charging and can thus reduce decomposition of the additive by rendering the SEI less soluble. Vinylene carbonate may be added at 0.1 to 5 weight percent of the electrolyte composition. The amount of vinylene carbonate can be adjusted so that the ratio between the vinylene carbonate and the additive containing a sulfonyl group (VC: -A-) is optimized to reduce the loading amount of vinylene carbonate while still providing a superior SEI layer for improved cell cycling Efficiency is maintained. In one example, the ratio between VC: A can be 1: 1. In another example, the ratio between VC: -A- may be 2: 1.5. In yet another example, the ratio between VC: -A- may be 2: 1.

Further, in the additive system, the anti-gas nucleating agent may be added to the electrolyte to reduce gas formation during the life of the cell. In some examples, anti-gassing agents may act to deactivate catalytic sites in cathode-active materials. Although anti-gassing agents typically increase the impedance of the cell, the presently disclosed electrolyte composition provides an improved and / or consistent level of impedance. In particular, the electrolyte composition of the present disclosure allows for reduced loading of an anti-gasliquoring agent which, together with the specific combination of the additive and the salt system, further reduces cell impedance.

In some exemplary embodiments, the anti-gassing agent may be present in less than 2.0 wt%, less than 1.5 wt%, or less than 1.0 wt% of the electrolyte composition. For example, the anti-gassing agent may be selected from at least one of 1,5,2,4-dioxadithiane 2,2,3,3-tetraoxides (MMDS), prop-1-ene-1,3-sultone (PRS), or 1 , 3 propane sultone. In another example, the anti-gassing agent may comprise at least one or more of the substances 1,5,2,4-dioxadithiane-2,2,3,3-tetraoxide (MMDS), prop-1-ene-1,3-sultone ( PRS), or 1,3-propane sultone.

In other examples, other anti-gassing agents may be chosen which reduce gas formation over the life of the cell. In one example, 1,3-propane sultone can be used. The anti-gas generating agent may be different from the at least one first additive containing a sulfonyl group and used in addition to the additive containing a sulfonyl group. It should be noted that the anti-gas-generating agents and the additive containing a sulfonyl group can act in different roles within the electrolyte.

In addition, as set forth above, the additive system may contain a second additive. A second additive can be used to reduce the loading amount of vinylene carbonate while maintaining good SEI development to improve cell cycle efficiency. The second additive may be present at less than 5% by weight of the electrolyte composition. For example, the second additive may be present at 0.1-5.0 wt%. In one embodiment, more than one second additive can be used which further reduces impedance while maintaining gas suppression and good cycle life over a wide temperature range. In one example, fluoroethylene carbonate (FEC) may be included as a second additive.

In addition to the additive system, the electrolyte composition comprises a salt system. The salt system includes a lithium salt and a co-salt. In particular, the salt system used for the nonaqueous electrolytic solution comprises a lithium salt in combination with a Co salt, whereby the Co salt is unlikely to produce Lewis acid decomposition products as a product of decomposition. The selected salt system retains the benefits of the lithium salt, for example LiPF ₆ salt, by combining the lithium salt with a Co salt, which does not show the disadvantages of LiPF ₆ . By selecting a Co salt in combination with the lithium salt, it is possible to address the strong Lewis acids derived from LiPF ₆ decomposition mechanisms, such as PF ₅ and OPF ₃ .

The lithium salt can be selected to have advantageous properties analogous to those of LiPF ₆ . For example, the lithium salt may be selected from the group consisting of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CFSO ₂ ) (C ₄ F ₉ SO ₂ ) and LiC (CF ₃ SO ₂ ) _{2 are} selected.

The Co salt can be selected from salts having at least one or more of the following properties: a salt that does not readily decompose; a salt that does not generate Lewis acidic species during decomposition, which further reduces gas formation via an electrolyte decomposition pathway; a salt which is resistant to protic solvents or protic impurities in the solvent system; a salt that is by nature less gas-forming; and a salt that has good conductivity at low temperatures and does not increase the impedance in the cell, especially at low temperatures. Further, the selected Co salt may have one or more of the following other properties: high solubility in carbonaceous solvents, good conductivity over a range of temperatures, and not increasing impedance. For example, a co-salt may be chosen that does not produce or produce any Lewis acid decomposition products upon decomposition. In one example, the Co salt can be chosen that does not produce Lewis acidic decomposition products during thermolysis.

By way of example and not limitation, the Co salt may include, for example, imide salts, triflate salts, organoborate salts and their fluorinated analogs. Case examples of imide salts may include bis (trifluoromethane) sulfonamide lithium salt (LiTFSI) and lithium bis-pentafluoroethanesulfonyl imide (LiBETI). Examples of triflate salts may include lithium trifluoromethanesulfonate (LiSO ₃ CF ₃ ). Examples of organo borate salts may include lithium bisoxalatoborate (LiBOB) and their fluorinated analogs such as lithium difluorobisoxalate borate (LIFOB).

In a particular embodiment, the salt system may contain LiPF ₆ and a sulfonamide lithium salt. As another non-limiting, specific example, the salt system _LiPF6 and LiTFSI may contain.

The salt system may contain the lithium salt at up to 2.0 M, or 0.5 M to 1.5 M or 0.5 M to 1.0 M. The Co salt can be present as a fraction of the total molar loading of the salts in the salt system. The Co salt may be present at up to 0.25 M or 0.05 M to 0.15 M.

In addition to the additive system and salt system, an organic solvent system may be included in the electrolyte composition. Examples of organic solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; Chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic esters, such as γ-valerolactone; Chain esters such as methyl acetate and methyl propionate; cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran and tetrahydropyran; Chain ethers such as dimethoxyethane and dimethoxymethane; cyclic phosphoric acid esters such as ethylene-methyl-phosphate and ethyl-ethylene-phosphate; Chain phosphoric acid esters such as trimethyl phosphate and triethyl phosphate; Halides thereof; sulfur-containing organic solvents not represented by the formula (1) and by vinyl ethylene carbonate (VEC) and fluoroethylene carbonate (FEC), poly (ethylene glycol) diacrylate. These organic solvents may be used singly or two or more of such solvents may be used in combination.

In one embodiment, the electrolyte composition may include a Co salt containing LiPF ₆ and LiTFSI, a solvent system including ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) and propylene carbonate (PC), ethylene sulfite (ES) as a sulfonyl group Additive present, vinylene carbonate (VC) and fluoroethylene carbonate (FEC) as an additional additive, and 1,3-propane sultone (PS) as an anti-gassing agent.

• (a) eine Zusammensetzung aus Li_x(M'_1-aM''_a)_y(XO₄)_z, Li_x(M'_1-aM''_a)_y(OXO₄)_z oder Li_x(M'_1-aM''_a)_y(X₂O₇)_z, mit einer Leitfähigkeit bei 27°C von mindestens etwa 10^–8 S/cm, wobei M' ein Übergangsmetall der ersten Reihe ist, X mindestens ein Phosphor, Schwefel, Arsen, Bor, Aluminium, Silizium, Vanadium, Molybdän und Wolfram ist, M'' eines oder mehrere der Gruppe IIA, IIIA, IVA, VA, VIA, VIIIA, VIIIA, IB, IIB, IIIB, IVB, VB und VIB Metall, 0,0001 < a ≤ 0,1 und x, y und z größer als 0 sind und Werte haben, so dass x plus y(1 – a)-mal der formellen Wertigkeit oder Wertigkeiten von M' plus ya-mal die formellen Wertigkeit oder Wertigkeiten von M'' gleich z-mal der formellen Wertigkeit von XO₄, X₂O₇ oder der OXO₄-Gruppe ist;
• (b) eine Zusammensetzung aus (Li_1-aM''_a)_xM'_y(XO₄)_z, (Li_1-aM''_a)_xM'_y(OXO₄)_z, oder (Li_1-aM''_a)_xM'_y(X₂O₇)_z, mit einer Leitfähigkeit bei 27°C von mindestens etwa 10 < –8 > S/cm, wobei M' eine Übergangsmetall der ersten Reihe ist, X mindestens ein Phosphor, Schwefel, Arsen, Bor, Aluminium, Silizium, Vanadium, Molybdän und Wolfram ist, M'' ist eines oder mehrere der Gruppe IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB und VIB Metall, 0,0001 < a ≤ 0,1 und x, y und z größer als 0 sind und Werte haben, so dass x plus y(1 – a)-mal der formellen Valenz oder Wertigkeit von M' plus ya-mal der formellen Valenz oder Wertigkeit von M'' gleich z-mal die formale Wertigkeit von XO₄, X₂O₇ oder der OXO₄-Gruppe ist;
• (c) eine Zusammensetzung aus (Li_b-a)M''_a)_xM'_y(XO₄)_z, (Li_b-a)M''_a)_xM'_y(OXO₄)_z, oder (Li_b-a)M''_a)_xM'_y(X₂O₇)_z, mit einer Leitfähigkeit bei 27 ° C von mindestens etwa 10^–8 S/cm, wobei M' ein Übergangsmetall der ersten Reihe ist, X mindestens ein Phosphor, Schwefel, Arsen, Bor, Aluminium, Silizium, Vanadium, Molybdän und Wolfram, M'' eines oder mehrere der Gruppe IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB und VIB Metall ist, 0,0001 < a ≤ 0,1, a ≤ b ≤ 1, und x, y und z größer als 0 sind und solche Werte haben, dass (b – a)x plus y(1 – a)-mal der formellen Valenz oder Wertigkeit von M' plus ya-mal die formale Wertigkeit oder Wertigkeiten von M'' gleich z-mal die formale Wertigkeit des XO₄, X₂O₇ oder OXO₄ Gruppe ist.

The rechargeable battery contains a positive electrode. In some examples, the positive, electrochemically active material may be a lithium metal oxide. For example, lithium cobalt oxide, LiCoO _{2 can be used} as a positive, electrochemically active material. In other examples, the positive, electrochemically active material may be a lithium transition metal oxoanion material selected from the group:

• (a) a composition of Li _x (M ' _1-a M " _a ) _y (XO ₄ ) _z , Li _x (M' _1-a M" _a ) _y (OXO ₄ ) _z or Li _x (M ' _1-a M'' _a ) _y (X ₂ O ₇ ) _z , having a conductivity at 27 ° C of at least about 10 ^-8 S / cm, where M' is a first row transition metal, X is at least one phosphorus, Sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of Group IIA, IIIA, IVA, VA, VIA, VIIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB Metal, 0.0001 <a ≤ 0.1 and x, y and z are greater than 0 and have values such that x plus y (1 - a) times the formal valence or valences of M 'plus ya times the formal valence or valences of M''equal to z times the formal valency of XO ₄ , X ₂ O ₇ or the OXO ₄ group is;
• (b) a composition of (Li _1-a M " _a ) _x M ' _y (XO ₄ ) _z , (Li _1-a M" _a ) _x M " _y (OXO ₄ ) _z , or (Li _{1 -a} M " _a ) _x M ' _y (X ₂ O ₇ ) _z , having a conductivity at 27 ° C of at least about 10 -8 S / cm, where M' is a first row transition metal, X is at least is phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB , VB and VIB metal, 0.0001 <a ≤ 0.1 and x, y and z are greater than 0 and have values such that x plus y (1 - a) times the formal valence or valence of M 'plus ya times the formal valence or valency of M "is equal to z times the formal valency of XO ₄ , X ₂ O ₇ or the OXO ₄ group;
• (c) a composition comprising (Li _ba) M '' _{a) x} M _'y (XO _{4) z,} (Li _ba) M'_{'a) x} M' _y (OXO _{4) z,} or (Li _ba) M '' _a ) _x M ' _y (X ₂ O ₇ ) _z , having a conductivity at 27 ° C of at least about 10 ^-8 S / cm, where M' is a first row transition metal, X is at least one phosphorus, sulfur, Arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M '' is one or more of Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metal, 0.0001 <a ≦ 0.1, a ≦ b ≦ 1, and x, y and z are greater than 0 and have such values that (b - a) x plus y (1 - a) times the formal valence or valency of M 'plus ya times the formal valence or valences of M''equal to z times the formal valence of the XO ₄ , X ₂ O ₇ or OXO ₄ group.

In other case examples, the cathode active material is a lithium transition metal phosphate compound having the formula (Li _1-x Z _x ) MPO ₄ , where M is one or more of vanadium, chromium, manganese, iron, cobalt, and nickel, Z is one or more of titanium, zirconium, niobium, aluminum, tantalum, tungsten or magnesium, and x ranges from 0 to 0.05 or Li _1-x MPO ₄ , where M is selected from the group consisting of vanadium, chromium, manganese, iron Cobalt and nickel; and 0 ≤ x ≤ 1.

In another example, the positive, electrochemically active material is lithium metal phosphate, for example, lithium iron phosphate. The positive, electrochemically active material may be in the form of powder or particles having a specific surface area of more than 5 m ² / g, 10 m ² / g, or greater than 15 m ² / g, or greater than 20 m ² / g, or even more than 30 m ² / g are present.

For example, the cathode may contain a lithium metal phosphate. In one case example, the lithium metal phosphate may be lithium iron phosphate LiFePO ₄ . Further, the LiFePO _{4 may have} an olivine structure and be prepared in the form of very small particles with high specific surface area, which are extremely stable in their delithiated form, even at elevated temperatures and in the presence of oxidizable organic solvents, e.g. Electrolyte, thereby enabling a safer Li-ion battery with very high charge and discharge rate capability, but also showing excellent retention of its lithium storage and aging capacity during many hundreds or even thousands of high-rate cycles.

The rechargeable battery contains a negative electrode capable of storing and releasing lithium. For example, the anode may contain electrochemically active graphite or silicon / graphite materials. In a case example in which a graphitic carbonaceous material is used, an artificial graphite made of soft (graphitizable) pitch of various origins produced by annealing, purified natural graphite; or these graphites which have undergone a variety of surface treatments can be used.

There is no limitation on the method of producing the negative or positive electrode using the above-mentioned active materials. In one case example, the electroactive material is mixed with a binder, a conductive material, solvent, etc., to prepare a suspension, which is then spread on a support material from a current collector, followed by drying to produce the electrode. Further, such an electrode material may be subjected to roll forming or compression molding to be processed into a film or a pellet, respectively.

The binder types for the production of the electrodes are not particularly limited as long as they are stable to the solvent and the electrolytic solution used in the production of the electrode. Examples of the binder include resinous polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide and cellulose; rubbery polymers such as styrene-butadiene rubber, isoprene rubber, butadiene rubber and ethylene-propylene rubber; thermoplastic elastomeric polymers such as styrene-butadiene-styrene block copolymer and its hydrogenated product, styrene-ethylene-styrene block copolymer and its hydrogenated product; flexible resinous polymers such as syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer and propylene-α-olefin (having 2 to 12 carbon atoms) - copolymer; and fluorocarbon polymers such as polyvinylidene fluoride, polytetrafluoroethylene and polytetrafluoroethylene-ethylene copolymer.

As a binder, it is also possible to use a polymer composition having an alkali metal ion conductivity (in particular, a lithium ion). As such, ion-conductive polymer compositions may be used in combination in a composite system made of polymeric compounds such as lithium salt or with an alkali metal salt.

The negative electrode material and the binder can be mixed in various ways. For example, particles of both may be mixed or particles of the negative electrode material may be entangled with fibrous binder to form a mixture, or a layer of the binder may be deposited on the surface of the particles of the negative electrode. In a case example, the mixing ratio of the binder to the negative electrode material may be 0.1 to 30% by weight of the negative electrode material. In another example, the mixing ratio of the binder to the negative electrode material may be 0.5 to 10 wt% of the negative electrode material. Addition of the binder in amounts greater than 30% by weight may increase the internal resistance of the electrode and amounts below 0.1% by weight may weaken the adhesive strength between the current collector and the negative electrode material.

By mixing the material of the negative electrode with the binder, a conductive material can be mixed together. Since the conductive material used is not limited in type, the conductive material may be a metal or a nonmetal. For example, a metallic conductive material may be composed of metal elements such as Cu or Ni. In another example, a non-metallic, conductive material may be carbon materials such as graphite, carbon black, acetylene black, and Ketjen black. The average particle diameter of the conductive material may be 1 μm or less.

In one example, a mixing ratio of the conductive material may be 0.1 to 30 wt% of the negative electrode material. In another example, the mixing ratio of the conductive material may be 0.5 to 15% by weight of the negative electrode material. A mixing ratio of the conductive additive in amounts greater than 0.1% by weight may provide a sufficiently formed conductive path between the conductive materials within the electrode.

The above-mentioned mixture containing at least the negative electrode material and the binder may be applied to a current collector foil. The application of the mixture to the current collector may be accomplished by techniques known to those skilled in the art. For example, if the mixture is a suspension, the suspension can be applied to the current collector by roll coating. In another example, when the mixture contains a solvent, the solvent may be dried to remove the solvent, whereby an electrode can be prepared.

The positive electrode containing the positive electroactive material has a specific surface area of the electrode measured using nitrogen adsorption using the Brunauer-Emmet-Teller (BET) method after densification or the calendering step, greater than 5 m ² / g is. A positive electrode may have a diameter of less than 125 μm, for example about 50 μm to 125 μm, or between about 80 μm to 100 μm on each side of the current collector and a pore volume fraction between about 40 and 70% by volume. The active material is typically loaded at about 10-20 mg / cm ² , and usually about 11-15 mg / cm ² .

The negative active material may consist of powder or particles having a specific surface area, as measured by nitrogen adsorption according to the Brunauer-Emmet-Teller (BET) method, of greater than about 2 m ² / g or 4 m ² / g or even about 6 m ² / g. The negative electrode may have a thickness of less than 75 μm to 65 μm, for example between about 20 and 65 μm or between about 40 μm to 55 μm on both sides of the current collector and a pore volume fraction between about 20 and 40% by volume. The active material may typically be at about 5-20 mg / cm ^2, or about 4-5 mg / cm ² are loaded.

It should be noted that there are no particular limitations on the production methods of the positive electrode, and a similar method may be used for a negative electrode as described above.

It should be noted that there are no specific limitations on the starting material or the morphology of the separator for the cell used in the present disclosure. The separator is used to separate the negative electrode and the positive electrode to avoid their physical contact. In one example, a separator may have high ion permeability and low electrical resistance. As materials for the separator, those which are excellent in stability to the electrolytic solution and in liquid holding properties can be preferably selected. For example, non-woven or porous film made of polyolefins such as polyethylene and polypropylene can be used as a separator in which the electrolytic solution is impregnated.

Methods for producing the nonaqueous electrolytic solution using such a nonaqueous electrolytic solution, negative electrode, positive electrode, outer container, and separator are not particularly limited, and may be selected from those commonly used. The non-aqueous electrolyte cell of the present invention may further comprise a gasket, a sealing plate, and a cell case besides such non-aqueous electrolyte solution, negative electrode, positive electrode, outer can or bag material, and separator. In one example, the non-aqueous electrolyte solution cell of the present disclosure may be prepared as a pouch due to low gas formation of the electrolyte over a wide temperature range.

The battery described herein exhibits advantageous characteristics over a wide temperature range in which the operation of the battery is expected. For example, the battery is able to operate between -30 ° C and + 60 ° C. Further, the battery with the disclosed electrolyte solution exhibits reduced gas formation and lower impedance. Lowered impedance of the battery is important for both increasing the performance at lower temperatures and extending battery life. The advantageous and unexpected properties can be achieved by an electrolyte composition containing organic solvents, a first additive containing a sulfonyl group, vinylene carbonate, an anti-gassing agent, a second additive for reducing the vinylene carbonate loading, and a salt system, wherein a lithium salt with a Co-salt is combined, where it is unlikely for the Co salt to produce Lewis acidic decomposition products comprises. The amount of vinylene carbonate can be adjusted to optimize the ratio between the additive, a sulfonyl group and vinylene carbonate to reduce the loading of vinylene carbonate while still maintaining a superior SEI layer for improved cell cycling efficiency.

In general, a thicker electrode layer (and higher active material loading) will provide a greater total battery capacity. However, thicker layers also increase electrode impedance. In contrast to conventional practice and in accordance with one or more embodiments, high-capacity thick layers may be used in a low-impedance (high-rate) cell. The use of an active material with a high specific surface area, while maintaining an adequate pore volume, achieves the desired capacity without increasing the impedance to unacceptably high levels.

With regard to the battery containers, the reduced gas formation of the electrolyte composition allows the use in pouches, as well as other constructions.

The selection of organic solvents in the electrolyte is also important in reducing impedance. In some embodiments, the electrolyte is advantageously free of γ-butyrolactone since γ-butyrolactone may undergo reductive oxidation at the negative electrode when the battery is charged (see Petibon et al, Journal of the Electrochemical Society, 160 (1) A117Al24 (2013) ). The resulting decomposition products can lead to blockage of the separator. The clogging can then increase the surface resistance of the negative electrode, thereby increasing the impedance at the anode, resulting in significant capacity loss in the charging cycle.

In addition, the use of the additive as represented by formula (1), in addition to vinylene carbonate (VC) in non-aqueous organic electrolytes, results in stable, low-resistance lithium-ion batteries. Without being bound by any particular theory, it appears that the additive lowers the impedance by reacting with the anode to provide a more ionically conductive SEI than an electrolyte without the additive. In addition, VC is efficient in passivating the carbon based anode during the initial charge. VC prevents the additive from decomposing by making the SEI less soluble.

The SEI comes from the thermodynamic instability of graphite-based anodes in organic electrolyte. When the battery is first charged, which is called a formation, the graphite reacts with the electrolyte. This forms a porous passivation layer, referred to as a solid electrolyte interface (SEI), which protects the anode from further attack, moderates the charge current, and limits current. This reaction also consumes little lithium. At high temperatures, or when the battery is running all the way down to zero cycling, the SEI may partially dissolve in the electrolyte. At high temperatures, the electrolyte may also decompose and accelerate side reactions, possibly leading to thermal instability. As the temperatures get lower, another layer of protection will form, but may consume more lithium, resulting in higher capacity losses. Thus, the stability of the SEI at high temperatures, an advantage of the battery described herein, is important in increasing the life of the battery. Furthermore, the battery described herein provides reduced gas formation over a wide temperature range.

However, if the SEI layer thickens too much, it actually becomes an obstacle to the lithium ions by increasing the impedance. The thickness of the SEI layer can affect the power output, which is important for electric vehicles.

One way to define cell impedance is to measure the area specific impedance. Impedance values are determined for the entire cell or for certain transitions, such as the anode or the cathode. Area Specific Impedance (ASI) is the impedance of a device normalized to the surface and is defined as the impedance measured at 1 kHz (Ω) using an LCZ meter or frequency response analyzer multiplied by the surface area of the opposing electrodes (cm ² ). This measurement is typically performed by applying a small (for example, 5 mV) sinusoidal voltage to the cell and measuring the resulting current. The resulting reaction can be described by in-phase and out-of-phase components. The in-phase (real or resistive) component of the impedance at 1 kHz is then reacted with the surface of opposing electrode multiplied (cm ²⁾ to give the area-specific impedance. The area specific impedance can be used to determine the impedance at the anode or at the cathode.

In one aspect, the rechargeable battery is used in a battery system that operates as a micro hybrid battery. Micro-hybrid batteries (or vehicles with start-stop function) allow the vehicle's internal combustion engine to stop when the vehicle is stationary, such as at a traffic light, saving fuel of up to 10% compared to conventional vehicles , When the driver releases the brake pedal to depress the gas, the engine is quickly restarted before the vehicle moves forward. While the development of the early generation of micro-hybrids has focused on smooth engine restart, next-generation systems are trying to harness the braking energy as a way to even greater fuel economy. The existing lead micro hybrid battery technology has some design limitations because it can not charge very fast and most of the vehicle braking energy is still lost. Li-ion chemistry batteries have a much higher rate of charge acceptance and are thus positioned to support the next generation micro-hybrid systems with higher rates of fuel economy improvement.

Micro hybrid batteries can be used as starter batteries for automotive engines. Their proximity to the engine and the location under the hood often does not allow for bulky heat management circuitry. Thus, the battery must be able to start the engine without heat supply at cold ambient temperatures, down to -30 ° C. In addition, the battery must be able to operate for extended periods of time under the temperatures of a running car engine (up to 60 ° C) without external cooling. Conventional lithium ion batteries suffer from high impedance at low temperatures, which reduces their ability to start a motor. In addition, low temperature power boost designs in lithium ion batteries often result in short high temperature service life. Although lead-acid batteries have improved the cold-start capabilities, they suffer short-term lifetimes compared to lithium-ion batteries for start-stop applications.

The nonaqueous electrolyte solution cell of the present invention has excellent low temperature properties and long term stability, as well as excellent cycle characteristics when used in a micro hybrid battery system. This technology improves the success of lithium-ion batteries in micro-hybrids, especially as starter batteries, because it increases the cold performance of the battery, allowing it to start the engine even in the worst cold temperatures. In addition, extending the life of the battery at high temperatures is essential because a common location for starter batteries is the engine compartment, where temperatures during vehicle operation are typically higher than ambient temperatures. Further, the non-aqueous electrolyte solution of the cell of the present invention has low gas evolution over the temperature range.

The present application will be explained in detail with reference to the following examples. Materials, amounts of uses, ratios, operations, and so forth, described below, may be changed without departing from the spirit of the present invention. The scope of the present invention is therefore not limited to specific examples described below. The disclosed electrolyte composition is useful in any form of battery, e.g. B. prismatic, button cell, cans, bags, etc. applicable.

An example of an electrolyte composition is given below. The electrolyte composition causes low gas formation over a wide temperature range. The electrolyte composition having gas formation reduced over a wide temperature range is an example of an electrolyte as described in the present application.

EXAMPLE 1

electrolyte composition

An example of an electrolyte composition according to the present disclosure includes LiPF 6 at 1.0 M, LiTFSI at 0.15 M, EC 40% by volume, EMC at 45% by volume, DEC at 10% by volume, PC at 5 Vol .-%, ES at 1.5 wt .-%, VC at 1 wt .-%, and PS at 1.5 wt .-%.

The electrolyte composition is compared to control electrolyte compositions, as described below and in U.S. Patent Nos. 4,199,866 and 5,629,644 1 to 10 explained. The electrolyte composition exhibits improved properties in low temperature, high temperature tests over the control electrolyte compositions.

A first control electrolyte composition comprises LiPF ₆ at 1.15 M, EC at 30% by volume, EMC at 55% by volume, DEC at 10% by volume, PC at 5% by volume, ES at 1% by weight % and VC at 2% by weight.

The first control electrolyte composition contains a first additive comprising a sulfonyl group, ES, but does not contain the saline or anti-gas additive of the current application.

A second control electrolyte composition comprises LiPF ₆ at 1.15 M, EC at 35 vol%, EMC at 40 vol%, DMC at 20 vol%, PC at 5 vol%, VC at 2, 5 wt .-%, triphenyl phosphite (TPPI) at 0.2 wt .-% and PS at 2 wt .-%. The second control electrolyte composition contains PS but does not contain a first additive, a sulfonyl group or a salt system.

The above example of electrolyte and control electrolyte compositions are referred to in the following figure descriptions. The cells can be constructed using graphite anode lithium iron phosphate (LFP) cathodes or graphite nickel-cobalt metal (NCM) cathodes. Other cathode / anode combinations possible.

In 1 there is shown an initial capacity loss for the formation and qualification of a cell with a lithium iron phosphate (LFP) cathode and a graphite anode. One LFP / graphite cell was made with the electrolyte composition described in Example 1, and another LFP / graphite cell was made with the first control electrolyte composition. The initial capacity loss for the new electrolyte with reduced gas formation during formation 101 and the qualification 102 shows improved initial capacity loss compared to the first control electrolyte composition in formation 103 and qualification 104 ,

In 2 An initial capacity loss for the formation and qualification of a cell with a nickel-cobalt-manganese (NCM) cathode and graphite anode is shown. An NCM / graphite cell was made with the electrolyte composition as described in Example 1, and another NCM / graphite cell was made with the second control electrolyte composition. The initial capacity loss for the new reduced gas formation electrolyte 201 shows improved initial capacity loss compared to the second control electrolyte composition 202 ,

Thus, the initial capacity loss data as shown in FIGS 1 and 2 It is shown that the new electrolyte composition gives better initial capacity loss compared to the first and second control electrolyte compositions under various test conditions.

In 3 , an AC resistance / DC resistance (ACR / DCR) impedance parity between the new electrolyte composition and the second control electrolyte composition in LFP / graphite cells is illustrated. The new electrolyte composition shows similar or lower impedance measurements for both the DCR (squares) and ACR (diamonds) compared to the first control electrolyte.

In 4 , an ACR impedance for cells with the electrolyte is illustrated in Example 1. Opposite the second control electrolyte 402 for cells with NCM cathodes and graphite anodes, shows the new electrolyte composition 401 an improved ACR impedance in NCM / graphite cells.

Thus, the new electrolyte composition retains / reduces the impedance as in the 3 and 4 is shown.

In the 5A and 5B is a hybrid pulse current capability (HPPC) test at 23 ° C for a 1 second pulse power ( 5A ) and 10 seconds of pulse power ( 5B ). The new electrolyte composition 501 shows a decrease in DCR during the HPPC test compared to the first control electrolyte composition 502 , All electrolytes were used in an LFP / Graphite cell.

In the 6A and 6B , illustrates a hybrid pulse current capability (HPPC) test at -20 ° C for a 1 second pulse power ( 6A ), and 10 seconds of pulse power ( 6B ). The new electrolyte composition 601 shows a significant decrease in DCR in HPPC tests compared to the first control electrolyte composition 602 , Thus, the new electrolyte composition exhibits improved low temperature performance. All electrolytes were used in an LFP / Graphite cell.

In 7 , the performance at 70% state of charge (SOC) during the cold start at -30 ° C shown. The new electrolyte composition 701 (solid lines) marked with the upper arrow shows increased performance compared to the first control electrolyte composition 702 (dashed lines), marked with arrow below. Thus, the new electrolyte composition exhibits improved low temperature performance.

In 8th the current during cold start is shown at -30 ° C for NCM / graphite cells. The new electrolyte composition 801 shows approximately a 20% increase in cold start performance compared to the second control electrolyte composition 802 , Consequently, the new electrolyte composition exhibits improved low temperature performance.

In 9 the cycle life of the NCM cathode / graphite anode cells is shown. The new electrolyte, black lines 901 , shows an improved lifetime compared to the second control electrolyte, gray lines 902 , Thus, the new electrolyte composition can extend the cycle life.

In 10 The gas volume after storage at 55 ° C in LFP / graphite cells is illustrated. The new electrolyte composition 1001 . 1002 . 1003 provides a gas formation level consistent with other acceptable electrolytes for use in bag designs, such as the second control electrolyte composition, over the course of Time0, Time1, and Time2 1004 . 1005 . 1006 , Thus, the new electrolyte composition gives little gas formation.

The disclosed electrolyte composition includes an additive system and salt system that provides a low gas-forming, wide temperature range cycling system. In one example, the disclosed composition comprises a non-aqueous electrolyte solution that includes a sulfonyl group, an anti-gassing agent, a second additive, and a salt system. The anti-gassing agent can reduce the gas formation of the additive containing a sulfonyl group, while the salt system containing a co-salt can reduce the amount of LiPF ₆ and the co-salt is unlikely to produce Lewis acid decomposition products. Further, in some examples, a second additive, such as FEC, is used to reduce the impedance and strengthen the SEI layer.

As briefly mentioned above, the new electrolyte composition can be used in a number of different types of battery designs, including in a bag design. For example, the anti-gassing properties of the disclosed composition can specifically improve use in a pouch.

An exemplary bag construction for use with the disclosed electrolyte composition is incorporated by reference in FIG 11 illustrated. The bag encloses positive and negative electrode sheets and is sealed around the positive and negative electrodes. For example, the bag material may comprise laminated layers including at least one of polyethylene, nylon, and aluminum foil. In one example, the inner components may be hermetically sealed within a housing made of the bag material. Other suitable materials can be used to seal the internal components of the cell.

The diagram in 11 shows various components of an example of a completely prismatic battery cell 200 comprising the collection tabs 304a . 304b , Extension tabs 308a . 308b , Welding section 604a . 604b and stripes 504a . 504b , A bag construction can be susceptible to seizure if there is strong gas formation in the cell. The use of the disclosed electrolyte composition in the pocket provides reduced gas formation, improved / retained impedance, improved cold-start performance, and use over a wide temperature range.

The foregoing discussion should be understood as illustrative and not be construed as limiting in any way. While the inventions have been more particularly described and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the inventions as defined by the claims.

The corresponding structures, materials, activities and equivalents of all means or steps plus functional elements in the appended claims are intended to encompass any structure, material or activities for performing the functions in combination with other claimed elements as specifically claimed.

Finally, it should be understood that the objects, systems and methods described hereinabove are embodiments of this disclosure - non-limiting examples for which numerous variations and extensions are also contemplated. Accordingly, this disclosure includes all novel and non-obvious combinations and subcombinations of the articles, systems and methods disclosed herein, and any and all equivalents thereof.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2013/188594 [0004]

Cited non-patent literature

• Petibon et al, Journal of the Electrochemical Society, 160 (1) A117Al24 (2013) [0075]

Claims (15)

A rechargeable battery comprising: a negative electrode capable of storing and releasing lithium; a positive electrode comprising a lithium transition metal oxoanion electroactive material (lithium transition metal oxoanion); a separator; a non-aqueous electrolyte solution comprising: a salt system, the salt system comprising a lithium salt present at 0.85 to 1.5 M, and a Co salt present at 0.05 to 0.25 M, wherein the co-salt does not produce Lewis acid degradation products; an additive system comprising: an anti-gelling agent, at least a first additive including the sulfonyl group represented by the formula (1): R ₁ -AR ₂ (1) wherein R ₁ and R ₂ independently represent an alkyl group which may be substituted with an aryl group or a halogen atom; an aryl group which may be substituted with an alkyl group or a halogen atom; or taken together to form, together with -A-, a cyclic structure which may contain an unsaturated bond in which "A" is represented by a formula selected from the group comprising:

and

a second additive, vinylene carbonate; and at least one organic solvent, wherein the nonaqueous electrolytic solution is free of γ-butyrolactone. The rechargeable battery of claim 1, wherein the first sulfonyl group-containing additive is present at 0.1% to 5% by weight of the electrolyte composition, and wherein the vinylene carbonate is present at 0.1% to 5% by weight. the electrolyte composition is present. A rechargeable battery according to claim 1, wherein the anti-gaslaking agent comprises at least one of 1,5,2,4-dioxadithiane-2,2,3,3-tetraoxide (MMDS), prop-1-ene-1,3-sultone (PrS ), or 1,3-propane sultone. The rechargeable battery of claim 1, wherein the anti-gaslaking agent is present at less than or equal to 2% by weight. A rechargeable battery according to claim 1, wherein the Co salt is selected from one of the salt classes comprising imide salts, triflate salts or organo borate salts or wherein the Co salt is bis (trifluoromethane) sulfonamide lithium salt (LiTFSI) is. The rechargeable battery of claim 1, wherein the lithium salt is selected from one of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN ( CFSO ₂ ) (C ₄ F ₉ SO ₂ ), and LiC (CF ₃ SO ₂ ) ₂ or wherein the lithium salt is present at 1.0 M and wherein the Co salt is present within 0.05 to 0.2 M. A rechargeable battery according to claim 1, wherein the second additive is fluoroethylene carbonate and is present at 1% by weight. A rechargeable battery according to claim 1, wherein the organic solvent is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, γ-valerolactone, methyl acetate and methyl propionate, tetrahydrofuran, 2-methyltetrahydrofuran and tetrahydropyran, dimethoxyethane and dimethoxymethane, ethylene-methyl phosphate and ethylethylene phosphate, trimethyl phosphate and triethyl phosphate, halides thereof, vinyl ethylene carbonate (VEC) and fluoroethylene carbonate (FEC), poly (ethylene glycol) diacrylate, and combinations thereof, or wherein the organic solvent comprises a mixture of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and propylene carbonate. A rechargeable battery according to claim 1, wherein the battery is contained in a pouch. A rechargeable battery according to claim 1, wherein said negative electrode comprises non-graphitizable carbon, artificial graphite or natural graphite compounds of carbonaceous materials with silicon or silica. The rechargeable battery of claim 1, wherein the positive electrode comprises a lithium transition metal oxide. A rechargeable battery according to claim 1, wherein the organic solution mixture contains 30% by volume of ethylene carbonate, 55% by volume of ethylmethyl carbonate, 10% by volume of diethyl carbonate and 5% by volume of propylene carbonate. An electrolyte composition for a rechargeable battery, comprising: a salt system, the salt system comprising a lithium salt present at 0.85 to 1.5 M, and a Co salt present at 0.05 M to 0.25 M, wherein the Co-salt Lewis acid degradation products likely not generated; an additive system comprising: at least a first additive comprising a sulfonyl group represented by the formula: R ₁ -AR ₂ (1) wherein R ₁ and R ₂ independently represent an alkyl group which may be substituted with an aryl group or a halogen atom; an aryl group which may be substituted with an alkyl group or a halogen atom; or taken together to form together with -A- a cyclic structure which may contain an unsaturated bond in which "A" is represented by a formula selected from the group comprising:

and

an anti-gassing agent, a second additive, and vinylene carbonate. The electrolyte composition of claim 13, further comprising a solution system, or wherein the first additive is present at 0.1 wt% to 5 wt%, the anti-gassing agent is present at less than or equal to 2 wt%, the second additive is present at 0.1 wt% to 5 wt%, and wherein the vinylene carbonate is present at 0.1 wt% to 5 wt%. The rechargeable battery of claim 1, wherein the second additive is present at less than or equal to 5% by weight of the electrolyte composition.

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