Flame retardant for battery electrolytes

Abstract

To provide a nonaqueous electrolyte solution for a lithium battery containing a flame retardant, and a lithium battery.SOLUTION: A non-aqueous electrolyte solution for a lithium battery includes a liquid electrolyte medium, a lithium-containing salt, 4-bromomethyl-1,3-dioxolan-2-one, and at least one electrochemical additive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to brominated flame retardants for use in battery electrolyte solutions. [Background technology]

[0002] One of the components that impacts the safety of lithium-ion batteries is the use of flammable solvents in lithium-containing electrolyte solutions. The inclusion of flame retardants in electrolyte solutions is one way to mitigate the flammability of these solutions. For a flame retardant to be a suitable component of an electrolyte solution, it must be soluble in the electrolyte, electrochemically stable over the battery's operating range, and have minimal adverse effects on battery performance. These adverse effects can include reduced electrical conductivity and / or chemical instability of the active material.

[0003] There is a need for flame retardants that can effectively suppress the flammability of lithium-ion batteries at a reasonable cost while minimizing the impact on the electrochemical performance of the batteries. Summary of the Invention

[0004] The present invention provides non-aqueous electrolyte solutions for lithium batteries containing an oxygen-containing brominated flame retardant, i.e., 4-bromomethyl-1,3-dioxolan-2-one, that extinguish fires in these non-aqueous electrolyte solutions, at least under laboratory conditions, in the presence of the oxygen-containing brominated flame retardant.

[0005] One embodiment of the present invention is a non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; iii) 4-bromomethyl-1,3-dioxolan-2-one; and iv) a) an unsaturated cyclic carbonate containing 3 to about 6 carbon atoms; b) a fluorine-containing saturated cyclic carbonate containing 3 to about 5 carbon atoms and 1 to about 4 fluorine atoms; c) a tris(trihydrocarbylsilyl)phosphite containing 3 to about 9 carbon atoms; d) a trihydrocarbylphosphine containing 3 to about 12 carbon atoms; e) cyclic sultones containing 3 to about 8 carbon atoms; f) saturated cyclic hydrocarbyl sulfites having 5- or 6-membered rings and containing 2 to about 6 carbon atoms; g) saturated cyclic hydrocarbyl sulfates having 5- or 6-membered rings and containing 2 to about 6 carbon atoms; h) cyclic dioxadithiopolyoxide compounds having 6-, 7-, or 8-membered rings and containing 2 to about 6 carbon atoms; i) another lithium-containing salt; and j) at least one electrochemical additive selected from a mixture of any two or more of the foregoing.

[0006] Another embodiment of the present invention is a non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; iii) 4-bromomethyl-1,3-dioxolan-2-one; and iv) at least one electrochemical additive selected from vinylene carbonate, 4-fluoro-ethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, lithium bis(oxalato)borate, lithium hexafluorophosphate, and a mixture of any two or more thereof.

[0007] Yet another embodiment of the present invention is a non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one.

[0008] These and other embodiments and features of the present invention will become further apparent from the following detailed description and appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0009] Throughout this specification, the phrase "electrolyte solution" is used interchangeably with the phrase "nonaqueous electrolyte solution."

[0010] The liquid electrolyte medium is comprised of one or more solvents that typically form the liquid electrolyte medium of the lithium electrolyte solution used in lithium batteries, and these solvents are polar, aprotic, stable to electrochemical cycling, and preferably have low viscosity. These solvents typically include acyclic carbonates, cyclic carbonates, ethers, sulfur-containing compounds, and esters of boric acid.

[0011] Solvents that can form the liquid electrolyte medium in the practice of the present invention include ethylene carbonate (1,3-dioxolan-2-one), dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, dioxolane, dimethoxyethane (glyme), tetrahydrofuran, methanesulfonyl chloride, 1,3,2-dioxathiolane 2-oxide, 1,3-propylene glycol borate, and mixtures of any two or more of the foregoing.

[0012] Preferred solvents include ethylene carbonate, ethyl methyl carbonate, and mixtures thereof. More preferred are mixtures of ethylene carbonate and ethyl methyl carbonate, especially in a volume ratio of about 20:80 to about 40:60, more preferably about 25:75 to about 35:65 ethylene carbonate:ethyl methyl carbonate.

[0013] Lithium-containing salts suitable for the practice of the present invention include lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium nitrate, lithium thiocyanate, lithium aluminate, lithium tetrachloroaluminate, lithium tetrafluoroaluminate, lithium tetraphenylborate, lithium tetrafluoroborate, lithium bis(oxalato)borate (LiBOB), lithium di(fluoro)(oxalato)borate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium titanate, lithium manganate, lithium cobaltate, lithium iodide ... Lithium-containing salts include lithium (LiCoO), lithium nickelate (LiNiO), lithium alkylcarbonate in which the alkyl group has 1 to 6 carbon atoms, lithium methylsulfonate, lithium trifluoromethylsulfonate, lithium pentafluoroethylsulfonate, lithium pentafluorophenylsulfonate, lithium fluorosulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (ethylsulfonyl)(trifluoromethylsulfonyl)imide, and mixtures of any two or more of the foregoing. Preferred lithium-containing salts include lithium hexafluorophosphate, lithium di(fluoro)(oxalato)borate, and lithium bis(oxalato)borate.

[0014] The typical concentration of the lithium-containing salt in the electrolyte solution is in the range of about 0.1 M to about 2.5 M, preferably about 0.5 M to about 2 M, more preferably about 0.75 M to about 1.75 M, and even more preferably about 0.95 M to about 1.5 M. When a plurality of lithium-containing salts form the lithium-containing electrolyte, the concentration refers to the total concentration of all the lithium-containing salts present in the electrolyte solution.

[0015] The electrolyte solution may contain other salts in addition to lithium salts, provided that such other salt(s) does not materially affect either the performance of the battery for the desired application or the flame retardancy of the electrolyte solution. In some embodiments, the only salt in the non-aqueous electrolyte solution is one or more lithium salts.

[0016] Suitable alkali metal salts that may be present in the electrolyte solution include sodium salts such as sodium chloride, sodium bromide, sodium iodide, sodium perchlorate, sodium nitrate, sodium thiocyanate, sodium aluminate, sodium tetrachloroaluminate, sodium tetrafluoroaluminate, sodium tetraphenylborate, sodium tetrafluoroborate, and sodium hexafluorophosphate; and potassium salts such as potassium chloride, potassium bromide, potassium iodide, potassium perchlorate, potassium nitrate, potassium thiocyanate, potassium aluminate, potassium tetrachloroaluminate, potassium tetrafluoroaluminate, potassium tetraphenylborate, potassium tetrafluoroborate, and potassium hexafluorophosphate.

[0017] Suitable alkaline earth metal salts that may be present in the electrolyte solution include magnesium salts such as magnesium chloride, magnesium bromide, magnesium iodide, magnesium perchlorate, magnesium nitrate, magnesium thiocyanate, magnesium aluminate, magnesium tetrachloroaluminate, magnesium tetrafluoroaluminate, magnesium tetraphenylborate, magnesium tetrafluoroborate, and magnesium hexafluorophosphate; and calcium salts such as calcium chloride, calcium bromide, calcium iodide, calcium perchlorate, calcium nitrate, calcium thiocyanate, calcium aluminate, calcium tetrachloroaluminate, calcium tetrafluoroaluminate, calcium tetraphenylborate, calcium tetrafluoroborate, and calcium hexafluorophosphate.

[0018] The oxygen-containing brominated flame retardant in the practice of the present invention is 4-bromomethyl-1,3-dioxolan-2-one, which can be represented by the following structural formula: [ka] In some cases, 4-bromomethyl-1,3-dioxolan-2-one is referred to by non-standard names such as 3-bromo-1,2-propylene carbonate.

[0019] In the practice of the present invention, 4-bromomethyl-1,3-dioxolan-2-one is miscible with the liquid medium of the non-aqueous electrolyte solution, where "miscible" means that 4-bromomethyl-1,3-dioxolan-2-one does not form a separate phase from the electrolyte solution. More specifically, 4-bromomethyl-1,3-dioxolan-2-one is miscible if it forms a single phase in a mixture of 30 wt.% ethylene carbonate and 70 wt.% ethyl methyl carbonate containing 1.2 M lithium hexafluorophosphate after 24 hours of shaking in a stirring device, and no separate phase forms after shaking is stopped. 4-bromomethyl-1,3-dioxolan-2-one does not precipitate from the non-aqueous electrolyte solution or form a suspension or slurry. It is recommended that the brominated flame retardant not cause precipitation of any of the other components of the non-aqueous electrolyte solution or the formation of a suspension or slurry, and preferable.

[0020] In the practice of the present invention, the amount of flame retardant in the non-aqueous electrolyte solution means that there is sufficient 4-bromomethyl-1,3-dioxolan-2-one present so that the solution passes the modified horizontal UL-94 test described below. The amount of flame retardant is typically about 25 wt. % of the flame retardant molecules, preferably about 26 wt. % or more of the flame retardant molecules, and more preferably about 27 wt. % or more of the flame retardant molecules, based on the total weight of the non-aqueous electrolyte solution. Similarly, the amount of flame retardant relative to the bromine content is typically about 11 wt. % or more of bromine (atoms), preferably about 11.4 wt. % or more of the bromine (atoms), based on the total weight of the non-aqueous electrolyte solution.

[0021] In some embodiments, 4-bromomethyl-1,3-dioxolan-2-one preferably has a bromine (atom) content of about 11 wt. % or more, more preferably about 11.4 wt. % or more, and even more preferably about 11.8 wt. % or more, based on the total weight of the solution. Preferably, the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof. More preferably, the lithium-containing salt is lithium hexafluorophosphate, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate.

[0022] In the practice of the present invention, the electrochemical additive is soluble in or miscible with the liquid medium of the non-aqueous electrolyte solution. The liquid form of the electrochemical additive is miscible with the liquid medium of the non-aqueous electrolyte solution, where "miscible" means that the electrochemical additive does not form a separate phase from the electrolyte solution. More specifically, an electrochemical additive is miscible if, after 24 hours of shaking in a stirring device, it forms a single phase in a mixture of 30 wt. % ethylene carbonate and 70 wt. % ethyl methyl carbonate containing 1.2 M lithium hexafluorophosphate; no separate phase forms after shaking is stopped; and the electrochemical additive does not precipitate from the non-aqueous electrolyte solution or form a suspension or slurry.

[0023] The term "soluble," as typically applied to solid electrochemical additives, refers to the fact that, upon dissolution, the electrochemical additive does not precipitate from the non-aqueous electrolyte solution or form a suspension or slurry. More specifically, an electrochemical additive is soluble if, after shaking for 24 hours in a stirring device, it dissolves in a mixture of 30% by weight ethylene carbonate and 70% by weight ethyl methyl carbonate containing 1.2 M lithium hexafluorophosphate and does not form a precipitate, suspension, or slurry after shaking is stopped.

[0024] 4-Bromomethyl-1,3-dioxolan-2-one, electrochemical additives, and mixtures thereof are generally stable to electrochemical cycling and preferably have low viscosity and / or do not significantly increase the viscosity of the electrolyte solution.

[0025] In various embodiments, the electrochemical additive is selected from a) unsaturated cyclic carbonates containing 3 to about 4 carbon atoms, b) fluorine-containing saturated cyclic carbonates containing 3 to about 4 carbon atoms and 1 to about 2 fluorine atoms, c) tris(trihydrocarbylsilyl)phosphites containing 3 to about 6 carbon atoms, d) trihydrocarbyl phosphates containing 3 to about 9 carbon atoms, e) cyclic sultones containing 3 to about 4 carbon atoms, f) saturated cyclic hydrocarbyl sulfites having a 5-membered ring and containing 2 to about 4 carbon atoms, g) saturated cyclic hydrocarbyl sulfates having a 5-membered ring and containing 2 to about 4 carbon atoms, h) cyclic dioxadithiopolyoxide compounds having a 6- or 7-membered ring and containing 2 to about 4 carbon atoms, i) another lithium-containing salt, and j) a mixture of any two or more of the foregoing.

[0026] In various embodiments, the electrochemical additive comprises: a) about 100% by weight of the total non-aqueous electrolyte solution; a) an unsaturated cyclic carbonate in an amount of about 0.5% to about 12% by weight, b) a fluorine-containing saturated cyclic carbonate in an amount of about 0.5% to about 8% by weight, based on the total weight of the non-aqueous electrolyte solution; c) a tris(trihydrocarbylsilyl)phosphite in an amount of about 0.1% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; d) a trihydrocarbyl phosphate in an amount of about 0.5% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; e) a cyclic sultone in an amount of about 0.25% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; g) a cyclic sultone in an amount of about 0.5% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; h) a saturated cyclic hydrocarbyl sulfate in an amount of about 0.25% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; i) a cyclic dioxadithiopolyoxide compound in an amount of about 0.5% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; j) another lithium-containing salt in an amount of about 0.5% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution; and k) a mixture of any two or more of the foregoing.

[0027] In some embodiments, the electrochemical additive is an unsaturated cyclic carbonate containing 3 to about 6 carbon atoms, preferably 3 to about 4 carbon atoms. Suitable unsaturated cyclic carbonates include vinylene carbonate (1,3-dioxol-2-one), 4-methyl-1,3-dioxol-2-one, and 4,5-dimethyl-1,3-dioxol-2-one. Vinylene carbonate is a preferred unsaturated cyclic carbonate. The unsaturated cyclic carbonate is preferably present in an amount of about 0.5 wt % to about 12 wt %, more preferably about 0.5 wt % to about 3 wt %, or about 8 wt % to about 11 wt %, based on the total weight of the nonaqueous electrolyte solution.

[0028] When the electrochemical additive is a fluorine-containing saturated cyclic carbonate containing 3 to about 5 carbon atoms, preferably 3 to about 4 carbon atoms, and 1 to about 4 fluorine atoms, preferably 1 to about 2 fluorine atoms, suitable fluorine-containing saturated cyclic carbonates include 4-fluoroethylene carbonate and 4,5-difluoroethylene carbonate. Preferably, the fluorine-containing saturated cyclic carbonate is 4-fluoroethylene carbonate. The fluorine-containing saturated cyclic carbonate is preferably present in an amount of about 0.5 wt % to about 8 wt %, more preferably about 1.5 wt % to about 5 wt %, based on the total weight of the nonaqueous electrolyte solution.

[0029] The tris(trihydrocarbylsilyl)phosphite electrochemical additive contains 3 to about 9 carbon atoms, preferably about 3 to about 6 carbon atoms. The trihydrocarbylsilyl groups may be the same or different. Suitable tris(trihydrocarbylsilyl)phosphites include tris(trimethylsilyl)phosphite, bis(trimethylsilyl)(triethylsilyl)phosphite, tris(triethylsilyl)phosphite, bis(trimethylsilyl)(triethylsilyl)phosphite, bis(trimethylsilyl)(tri-n-propylsilyl)phosphite, and tris(tri-n-propylsilyl)phosphite. Tris(trimethylsilyl)phosphite is the preferred tris(trihydrocarbylsilyl)phosphite. The amount of tris(trihydrocarbylsilyl)phosphite is preferably about 0.1% by weight to about 5% by weight, more preferably about 0.15% by weight to about 4% by weight, and even more preferably about 0.2% by weight to about 3% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0030] In some embodiments, the electrochemical additive is a trihydrocarbyl phosphate containing 3 to about 12 carbon atoms, preferably 3 to about 9 carbon atoms. The hydrocarbyl groups can be saturated or unsaturated, and the hydrocarbyl groups of the trihydrocarbyl phosphates can be the same or different. Suitable trihydrocarbyl phosphates include trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, tri- Examples of the trihydrocarbyl phosphate include n-propyl phosphate, triallyl phosphate, and trivinyl phosphate. Triallyl phosphate is a preferred trihydrocarbyl phosphate. The trihydrocarbyl phosphate is generally present in an amount of about 0.5% to about 5% by weight, preferably about 1% to about 5% by weight, and more preferably about 2% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0031] When the electrochemical additive is a cyclic sultone containing 3 to about 8 carbon atoms, preferably 3 to about 4 carbon atoms, suitable cyclic sultones include 1,3-propane sultone (1-propane-1,3-sultone), 1,3-propene sultone (1-propene-1,3-sultone), 1,3-butane sultone (5-methyl-1,2-oxathiolane 2,2-dioxide), 2,4-butane sultone (3-methyl-1,2-oxathiolane 2,2-dioxide), 1,4-butane sultone (1,2-oxathiane 2,2-dioxide), 2-hydroxy-alpha-toluenesulfonic acid sultone (3H-1,2-benzoxathiole 2,2-dioxide), and 1,8-naphthosultone. Preferred cyclic sultones include 1,3-propane sultone and 1,3-propene sultone. The cyclic sultone is preferably present in an amount of about 0.25 wt % to about 5 wt %, more preferably about 0.5 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution. In some embodiments, the cyclic sultone is preferably present in an amount of about 1.5 wt % to about 12 wt %, based on the total weight of the non-aqueous electrolyte solution.

[0032] The saturated cyclic hydrocarbyl sulfite electrochemical additive contains 2 to about 6 carbon atoms, preferably 2 to about 4 carbon atoms, and has a 5- or 6-membered ring, preferably a 5-membered ring. One or more substituents, such as methyl or ethyl groups, preferably one or more methyl groups, can be present on the ring; more preferably, there are no substituents on the ring. Suitable saturated cyclic hydrocarbyl sulfites include 1,3,2-dioxathiolane 2-oxide (1,2-ethylene sulfite), 1,2-propanediol sulfite (1,2-propylene sulfite), 4,5-dimethyl-1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiane 2-oxide, and 4-methyl-1,3-dioxathiane 2-oxide (1,3-butylene sulfite). Preferred cyclic hydrocarbyl sulfites include 1,3,2-dioxathiolane 2-oxide (1,2-ethylene sulfite). The amount of the cyclic hydrocarbyl sulfite is preferably about 0.5% by weight to about 5% by weight, more preferably about 1% by weight to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0033] In some embodiments, the electrochemical additive is a saturated cyclic hydrocarbyl sulfate containing 2 to about 6 carbon atoms, preferably 2 to about 4 carbon atoms, and having a 5- or 6-membered ring, preferably a 5-membered ring. One or more substituents, such as methyl or ethyl groups, preferably one or more methyl groups, can be present on the ring, and more preferably there are no substituents on the ring. Suitable saturated cyclic hydrocarbyl sulfates include 1,3,2-dioxathiolane 2,2-dioxide (1,2-ethylene sulfate), 1,3,2-dioxathiane 2,2-dioxide (1,3-propylene sulfate), 4-methyl-1,3,2-dioxathiane 2,2-dioxide (1,3-butylene sulfate), and 5,5-dimethyl-1,3,2-dioxathiane 2,2-dioxide. The saturated cyclic hydrocarbyl sulfate is preferably present in an amount of about 0.25% by weight to about 5% by weight, more preferably about 1% by weight to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0034] When the electrochemical additive is a cyclic dioxadithiopolyoxide compound, the cyclic dioxadithiopolyoxide compound contains 2 to about 6 carbon atoms, preferably 2 to about 4 carbon atoms, and has a 6-, 7-, or 8-membered ring. The dioxadithiopolyoxide compounds contain 2 to about 4 carbon atoms and have a 6- or 7-membered ring. One or more substituents, such as methyl or ethyl groups, preferably one or more methyl groups, can be present on the ring; more preferably, no substituents are present on the ring. Suitable cyclic dioxadithiopolyoxide compounds include 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, 1,5,2,4-dioxadithiepane 2,2,4,4-tetraoxide (cyclodisone), 3-methyl-1,5,2,4-dioxadithiepane 2,2,4,4-tetraoxide, and 1,5,2,4-dioxadithiocane 2,2,4,4-tetraoxide. 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide is preferred. The amount of the cyclic dioxadithiopolyoxide compound is preferably about 0.5% by weight to about 5% by weight, more preferably about 1% by weight to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0035] The phrases "another lithium-containing salt" and "other lithium-containing salt" indicate that at least two lithium salts are used in preparing the electrolyte solution. When the electrochemical additive is another lithium-containing salt, it is preferably present in an amount of about 0.5 wt % to about 5 wt %, more preferably about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution. Suitable lithium-containing salts include all of the lithium-containing salts described above. Lithium di(fluoro)(oxalato)borate and lithium bis(oxalato)borate are preferred.

[0036] A mixture of any two or more of the aforementioned electrochemical additives can be used, including various electrochemical additives of the same type and / or different types. When a mixture of electrochemical additives is used, the total amount of electrochemical additives is about 0.25% to about 5% by weight, more preferably about 0.5% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution. A mixture of an unsaturated cyclic carbonate and a saturated cyclic hydrocarbyl sulfite, or a mixture of a cyclic sultone, a tris(trihydrocarbylsilyl)phosphite, and a cyclic dioxadithiopolyoxide compound is preferred.

[0037] Preferred types of electrochemical additives include saturated cyclic hydrocarbyl sulfates, cyclic sultones, and other lithium-containing salts, especially when not used together with other electrochemical additives. More preferably, the saturated cyclic hydrocarbyl sulfates are present in an amount of about 1 wt % to about 4 wt %, the cyclic sultones in an amount of about 0.5 wt % to about 4 wt %, or about 1.5 wt % to about 12 wt %, and the other lithium-containing salts in an amount of about 1 wt % to about 4 wt %, respectively, based on the total weight of the non-aqueous electrolyte solution.

[0038] Electrochemical additives such as vinylene carbonate, 4-fluoroethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, lithium di(fluoro)(oxalato)borate, lithium bis(oxalato)borate, and lithium hexafluorophosphate When selected from the group consisting of 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propane sultone, 1,3-propene sultone, tris(trimethylsilyl)phosphite, and lithium bis(oxalato)borate, the electrochemical additive is preferably 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propene sultone, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate, more preferably 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propene sultone, lithium di(fluoro)(oxalato)borate, and lithium bis(oxalato)borate. The amounts and preferences thereof are as described above.

[0039] In yet another embodiment, 4-bromomethyl-1,3-dioxolan-2-one is preferred. Preferably, the amount of bromine (atoms) is about 10% by weight or more, more preferably about 11% by weight or more, based on the total weight of the solution. Preferably, the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof. More preferably, the lithium-containing salt is lithium hexafluorophosphate, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate.

[0040] Additional components often included in electrolyte solutions for lithium batteries can also be present in the electrolyte solution of the present invention. Such additional components include succinonitrile and silazane compounds such as hexamethyldisilazane. Typically, the amount of any optional component ranges from about 1 wt % to about 5 wt %, preferably from about 2 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution.

[0041] Another embodiment of the present invention provides a process for producing a non-aqueous electrolyte solution for a lithium battery. The process includes combining components including: i) a liquid electrolyte medium; ii) a lithium-containing salt; iii) 4-bromomethyl-1,3-dioxolan-2-one; and iv) at least one electrochemical additive as described above. The 4-bromomethyl-1,3-dioxolan-2-one is present in the electrolyte solution in a flame retardant amount. The components can be combined in any order, but it is preferred that all components are added to the liquid electrolyte medium. The liquid electrolyte medium, lithium-containing salt, electrochemical additive(s), and the amounts of each component are as described above.

[0042] Yet another embodiment of the present invention provides a process for producing a non-aqueous electrolyte solution for a lithium battery, the process comprising combining components including: i) a liquid electrolyte medium, ii) a lithium-containing salt, iii) 4-bromomethyl-1,3-dioxolan-2-one, and iv) at least one electrochemical additive selected from vinylene carbonate, 4-fluoroethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, lithium di(fluoro)(oxalato)borate, lithium bis(oxalato)borate, lithium hexafluorophosphate, and a mixture of any two or more thereof. The liquid electrolyte medium, lithium-containing salt, electrochemical additive(s), and the amounts of each component are as described above.

[0043] In some preferred embodiments, the electrochemical additive is vinylene carbonate in an amount of about 0.5 wt % to about 3 wt % based on the total weight of the non-aqueous electrolyte solution, and in other preferred embodiments, the electrochemical additive is vinylene carbonate in an amount of about 8 wt % to about 11 wt % based on the total weight of the non-aqueous electrolyte solution.

[0044] In some preferred embodiments, the electrochemical additive is 4-fluoro-ethylene carbonate in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0045] In some preferred embodiments, the electrochemical additive is tris(trimethylsilyl)phosphite in an amount of about 0.2% to about 3% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0046] In some preferred embodiments, the electrochemical additive is triallyl phosphate in an amount of about 1% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0047] In some preferred embodiments, the cyclic sultone is present in an amount of about 100% by weight based on the total weight of the non-aqueous electrolyte solution. , 1,3-propane sultone, or 1,3-propene sultone in an amount of about 0.5% to about 4% by weight.

[0048] In some preferred embodiments, the cyclic sultone is 1,3-propane sultone in an amount of about 1.5 wt % to about 12 wt %, based on the total weight of the non-aqueous electrolyte solution.

[0049] In some preferred embodiments, the electrochemical additive is 1,3,2-dioxathiolane 2-oxide (ethylene sulfite) in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0050] In some preferred embodiments, the electrochemical additive is 1,3,2-dioxathiolane 2,2-dioxide (ethylene sulfate) in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0051] In some preferred embodiments, the electrochemical additive is 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0052] In some preferred embodiments, the electrochemical additive is lithium bis(oxalato)borate in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0053] In some preferred embodiments, the electrochemical additive is lithium di(fluoro)(oxalato)borate in an amount of about 1% to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution.

[0054] A mixture of any two or more of the aforementioned electrochemical additives can be used. When a mixture of electrochemical additives is used, the total amount of the electrochemical additives is about 0.25% by weight to about 5% by weight, more preferably about 0.5% by weight to about 4% by weight, based on the total weight of the non-aqueous electrolyte solution. A mixture of vinylene carbonate and 1,3,2-dioxathiolane 2-oxide, a mixture of vinylene carbonate and 1,3-propane sultone, or a mixture of 1,3-propene sultone, tris(trimethylsilyl)phosphite, and 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide is preferred.

[0055] Preferred electrochemical additives include 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propene sultone, 1,3-propane sultone, tris(trimethylsilyl)phosphite, lithium di(fluoro)(oxalato)borate, and lithium bis(oxalato)borate, especially when not used in conjunction with other electrochemical additives. More preferably, 1,3,2-dioxathiolane 2,2-dioxide is contained in an amount of about 1 wt % to about 4 wt %, 1,3-propene sultone in an amount of about 0.5 wt % to about 4 wt %, 1,3-propane sultone in an amount of about 0.5 wt % to about 4 wt %, 1,3-propane sultone in an amount of about 1.5 wt % to about 12 wt %, tris(trimethylsilyl)phosphite in an amount of about 0.2 wt % to about 3 wt %, lithium di(fluoro)(oxalato)borate in an amount of about 1 wt % to about 4 wt %, and lithium bis(oxalato)borate in an amount of about 1 wt % to about 4 wt %, respectively, relative to the total weight of the nonaqueous electrolyte solution.

[0056] Yet another embodiment of the present invention provides a process for producing a non-aqueous electrolyte solution for a lithium battery. The process includes combining components including: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one. The 4-bromomethyl-1,3-dioxolan-2-one is present in the electrolyte solution in a flame retardant amount. The components can be combined in any order, but all components should be combined in a liquid state. Preferably, the liquid electrolyte medium, the lithium-containing salt, and the amounts of each component are as described above.

[0057] Another embodiment of the present invention provides a process for producing a non-aqueous electrolyte solution for a lithium battery, the process comprising combining components including: i) a liquid electrolyte medium, ii) a lithium-containing salt, and iii) 4-bromomethyl-1,3-dioxolan-2-one.

[0058] The non-aqueous electrolyte solution of the present invention, which contains 4-bromomethyl-1,3-dioxolan-2-one and typically one or more electrochemical additives, is typically used in a non-aqueous lithium battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte solution. The non-aqueous lithium battery can be obtained by injecting the non-aqueous electrolyte solution between a negative electrode and a positive electrode, optionally with a separator therebetween.

[0059] The following examples are presented for illustrative purposes and are not intended to impose limitations on the scope of the present invention.

[0060] In Example 1, a modified horizontal UL-94 test was performed. This modified horizontal UL-94 test is very similar to known published horizontal UL-94 tests. See, for example, Otsuki, M. et al. "Flame-Retardant Additives for Lithium-Ion Batteries." Lithium-Ion Batteries. Ed. M. Yoshio et al. New York, Springer, 2009, pp. 275-289. The modified UL-94 test was as follows:

[0061] Cores were cut from cylindrical fiberglass cores, the cut edges smoothed, and dust and particles removed from the core surface. Before testing, the cores were dried at 120°C for 20 hours. The core length was 5±0.1 inches (12.7±0.25 cm). Each specimen to be tested was prepared in a 4-ounce (120 mL) glass bottle in a dry box. The desired amount of flame retardant and, if present, electrochemical additives were combined with the desired amount of simple electrolyte solution. For example, a flame-retardant-containing electrolyte solution was formed by combining 8 wt% brominated flame retardant, 2 wt% electrochemical additive, and 90 wt% simple electrolyte solution. Before combining with the flame retardant, the simple electrolyte solution contained 1.2 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (3:7 weight ratio) in a 4-ounce (120 mL) glass bottle. Each core was immersed in the electrolyte solution for 30 minutes. Each specimen was removed from the electrolyte solution, held over the electrolyte solution until no more dripping occurred, and then placed in a 4-oz (120 mL) glass jar. The cap was closed to prevent evaporation of the electrolyte solution. The burner was ignited and adjusted to produce a blue flame 20 ± 1 mm high. The specimen was removed from the 4-oz (120 mL) glass jar and placed on a metal support fixture in a horizontal position, secured by one end of the wick. If an exhaust fan was running, it was turned off for testing. The flame was at a 45 ± 2° angle relative to the horizontal wick. One way to achieve this, if the burner had a burner tube, was to tilt the center axis of the burner tube toward the end of the specimen at a 45 ± 2° angle from the horizontal. Without changing the specimen's position, the flame was applied to the free end of the specimen for 30 ± 1 s. The burner was removed after 30 ± 1 s or just after the specimen's burn front reached the 1-inch (2.54 cm) mark. If the specimen continued to burn after the test flame was removed, the time in seconds until the flame was extinguished or the burn front (flame) moved from the 1 inch (2.54 cm) mark to the 4 inch (10.16 cm) mark was recorded.

[0062] If the flame goes out when the burner is removed, the specimen is considered "not flammable." If the flame was extinguished before reaching the 1 inch (2.54 cm) mark, the specimen was considered "flame retardant." If the flame was extinguished before reaching the 4 inch (10.16 cm) mark, the specimen was considered "self-extinguishing."

[0063] Each modified horizontal UL-94 test result reported below is the average of three runs.

[0064] Example 1 The non-aqueous electrolyte solutions containing 4-bromomethyl-1,3-dioxolan-2-one prepared as described above were subjected to the modified UL-94 test described above. The results are summarized in Table 1 below. As noted above, the reported values ​​are the average of three runs. [Table 1]

[0065] Example 2 Additional flammability testing of non-aqueous electrolyte solutions was conducted at Sandia National Laboratories. These high-temperature tests approximated the conditions under which a hot electrolyte must be non-flammable, particularly in conjunction with an ignition source for venting. Testing was performed by filling an 18650-size battery cell with approximately 5 mL of non-aqueous electrolyte solution, crimping the cell with a conventional cell header assembly, and heating the electrolyte-containing cell at a constant rate of 5 °C / min with a spark-wire ignition source located in a fixed position approximately 2 inches above the cell header. At approximately 200 °C, the battery cell initiated venting, aerosolizing the hot electrolyte solution and exposing it to the spark-wire ignition source. Each sample was monitored for ignition. Non-ignition was considered a passing test, while ignition was considered a failing test.

[0066] One sample contained a non-aqueous electrolyte solution containing 1.2 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (3:7 weight ratio) without any flame retardant. The remaining samples contained the desired amount of flame retardant in the electrolyte solution. The results are summarized in Table 2 below. Zero flame duration (no ignition) is optimal, and shorter flame durations are better than longer ones. The results below show that the flame retardant significantly reduced flame duration, as evidenced by the shorter flame duration compared to the electrolyte solution. [Table 2]

[0067] Example 3 Several flame retardant tests were also conducted on coin cells. Coin cells were assembled using nonaqueous electrolyte solutions containing the desired amount of flame retardant. The coin cells were then subjected to CCCV electrochemical cycling, charging to 4.2 V at C / 5, with a current interrupt at C / 50 in the CV portion, and CC discharge to 3.0 V at C / 5.

[0068] One sample contained 1.2 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (3:7 weight ratio), a nonaqueous electrolyte solution without flame retardant. The remaining samples contained the desired amount of flame retardant in the electrolyte solution. Some solutions also contained electrochemical additives in addition to the flame retardant. The results are summarized in Tables 3A-3D below. The error range for coulombic efficiency is approximately ±0.5% to approximately ±1.0%. The results reported in Tables 3A-3C are averages of multiple cells unless otherwise noted. "Multiple cells" typically refers to two or three cells. [Table 3] [Table 4-1] [Table 4-2] [Table 5]

[0069] Some flame retardants were tested in coin cells up to 100 cycles. The results are reported below in Table 3D. The data for each flame retardant below is reported from the best performing single cell. [Table 6]

[0070] Any component referred to by chemical name or formula anywhere in this specification or in the claims, whether referred to in the singular or plural, is identified as being present prior to contact with another substance (e.g., another component, solvent, etc.) referred to by that chemical name or chemical form. It does not matter what chemical change, transformation, and / or reaction occurs in the resulting mixture or solution, since such change, transformation, and / or reaction is the natural result of bringing the particular components together under the conditions required in accordance with this disclosure. The component is therefore identified as a component that is brought together in connection with performing a desired operation or forming a desired composition. Also, the following claims, even when referring to a substance, component, and / or ingredient in the present tense (e.g., "comprising," "being," etc.), refer to the substance, component, or ingredient as if it existed immediately prior to its first contact, blending, or mixing with one or more other substances, components, and / or ingredients in accordance with this disclosure. The fact that substances, components, or ingredients may have lost their original identity due to chemical reaction or transformation in the course of the contacting, blending, or mixing operation, when carried out in accordance with this disclosure and the ordinary skill of a chemist, is therefore of no practical importance.

[0071] The present invention may comprise, consist of, or consist essentially of the materials and / or procedures recited herein.

[0072] As used herein, the term "about" modifying the amount of an ingredient in a composition or used in a method of the invention is intended to be within the scope of the present invention and is not intended to be limiting unless otherwise specified, for example, by typical measurements and liquid handling procedures used to make concentrates or use solutions in the real world; The term "about" refers to variations in numerical quantities that may result from variations in the amount of a compound; differences in the manufacture, source, or purity of ingredients used to make the composition or carry out the process; and the like. The term "about" also encompasses amounts that differ due to different equilibrium conditions of a composition resulting from a particular initial mixture. Whether or not modified by the term "about," the claims encompass the equivalent of the quantity.

[0073] As used herein, the article "a" or "an," when used herein, unless expressly stated otherwise, is not intended to, and should not be construed as, limiting the detailed description or claims to the single element referred to by the article. Rather, the article "a" or "an," when used herein, is intended to cover one or more such elements, unless the context clearly indicates otherwise.

[0074] This invention is susceptible to considerable variation in its practice. Therefore, the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove.

Claims

1. 1. A non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one, iv) a) unsaturated cyclic carbonates containing from 3 to about 6 carbon atoms; b) fluorine-containing saturated cyclic carbonates containing from 3 to about 5 carbon atoms and from 1 to about 4 fluorine atoms; c) tris(trihydrocarbylsilyl)phosphites containing from 3 to about 9 carbon atoms; d) trihydrocarbyl phosphates containing from 3 to about 12 carbon atoms; e) cyclic sultones containing from 3 to about 8 carbon atoms; f) saturated cyclic hydrocarbyl sulfites having five or six membered rings and containing from 2 to about 6 carbon atoms; g) saturated cyclic hydrocarbyl sulfates having five or six membered rings and containing from 2 to about 6 carbon atoms; h) cyclic dioxadithiopolyoxide compounds having 6-, 7-, or 8-membered rings and containing from 2 to about 6 carbon atoms; i) another lithium-containing salt, and j) at least one electrochemical additive selected from the group consisting of: a mixture of any two or more of the foregoing.

2. The electrochemical additive is a) unsaturated cyclic carbonates containing from 3 to about 4 carbon atoms; b) fluorine-containing saturated cyclic carbonates containing 3 to about 4 carbon atoms and 1 to about 2 fluorine atoms; c) tris(trihydrocarbylsilyl)phosphites containing from 3 to about 6 carbon atoms; d) trihydrocarbyl phosphates containing from 3 to about 9 carbon atoms; e) cyclic sultones containing from 3 to about 4 carbon atoms; f) saturated cyclic hydrocarbyl sulfites having a five-membered ring and containing from 2 to about 4 carbon atoms; g) saturated cyclic hydrocarbyl sulfates having a five-membered ring and containing from 2 to about 4 carbon atoms; h) cyclic dioxadithiopolyoxide compounds having six- or seven-membered rings and containing from 2 to about 4 carbon atoms; i) another lithium-containing salt, and j) a mixture of any two or more of the foregoing.

3. The electrochemical additive is a) an unsaturated cyclic carbonate in an amount of about 0.5 wt % to about 12 wt %, based on the total weight of the non-aqueous electrolyte solution; b) a fluorine-containing saturated cyclic carbonate in an amount of about 0.5 wt % to about 8 wt %, based on the total weight of the non-aqueous electrolyte solution; c) tris(trihydrocarbylsilyl)phosphite in an amount of about 0.1 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; d) a trihydrocarbyl phosphate in an amount of about 0.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; e) a cyclic cation in an amount of about 0.25 wt % to about 5 wt % based on the total weight of the nonaqueous electrolyte solution; Sultanahmet, f) a cyclic sultone in an amount of about 1.5 wt % to about 12 wt %, based on the total weight of the non-aqueous electrolyte solution; g) a saturated cyclic sulfite in an amount of about 0.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; h) a saturated cyclic hydrocarbyl sulfate in an amount of about 0.25 wt. % to about 5 wt. %, based on the total weight of the non-aqueous electrolyte solution; i) a cyclic dioxadithiopolyoxide compound in an amount of about 0.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; j) another lithium-containing salt in an amount of about 0.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; and j) a mixture of any two or more of the foregoing.

4. The solution of any of claims 1 to 3, wherein the electrochemical additive is a saturated cyclic hydrocarbyl sulfate, a cyclic sultone, or another lithium-containing salt.

5. 2. The solution of claim 1, wherein the electrochemical additive is a saturated cyclic hydrocarbyl sulfate in an amount of about 1 wt % to about 4 wt %, a cyclic sultone in an amount of about 0.5 wt % to about 4 wt %, a cyclic sultone in an amount of about 1.5 wt % to about 12 wt %, a tris(trihydrocarbylsilyl)phosphite in an amount of about 0.2 wt % to about 3 wt %, or another lithium-containing salt in an amount of about 1 wt % to about 4 wt %, each based on the total weight of the non-aqueous electrolyte solution.

6. 6. The solution of claim 1 or claim 5, wherein the electrochemical additive is 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propene sultone, 1,3-propane sultone, tris(trimethylsilyl)phosphite, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate.

7. 7. The solution of claim 5 or claim 6, wherein each electrochemical additive is not used with other electrochemical additives.

8. 4. The solution of claim 1, wherein the electrochemical additive is a mixture of an unsaturated cyclic carbonate and a saturated cyclic hydrocarbyl sulfite, or a mixture of a cyclic sultone, a tris(trihydrocarbylsilyl) phosphite, and a cyclic dioxadithiopolyoxide.

9. 9. The solution of claim 8, wherein the total amount of the electrochemical additives in each mixture is from about 0.25% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution.

10. 10. The solution of claim 1, wherein 4-bromomethyl-1,3-dioxolan-2-one is in an amount of about 10% by weight or more of bromine, based on the total weight of the solution.

11. 10. The solution of claim 1, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate.

12. 10. The solution of claim 1, wherein the non-aqueous electrolyte solution further comprises vinylene carbonate in an amount of about 8% to about 11% by weight, based on the total weight of the non-aqueous electrolyte solution.

13. A non-aqueous lithium battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte solution according to any one of claims 1 to 12. Umm battery.

14. 1. A non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one, iv) at least one electrochemical additive selected from vinylene carbonate, 4-fluoroethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, lithium di(fluoro)(oxalato)borate, lithium bis(oxalato)borate, and a mixture of any two or more thereof.

15. The electrochemical additive is vinylene carbonate in an amount of about 0.5 wt % to about 3 wt %, based on the total weight of the non-aqueous electrolyte solution; vinylene carbonate in an amount of about 8 wt % to about 11 wt %, based on the total weight of the non-aqueous electrolyte solution; 4-fluoro-ethylene carbonate in an amount of about 1.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; tris(trimethylsilyl)phosphite in an amount of about 0.2 wt % to about 3 wt %, based on the total weight of the non-aqueous electrolyte solution; triallyl phosphate in an amount of about 1 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; 1,3-propane sultone or 1,3-propene sultone in an amount of about 0.5 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; 1,3-propane sultone in an amount of about 1.5 wt % to about 12 wt %, based on the total weight of the non-aqueous electrolyte solution; 1,3,2-dioxathiolane 2-oxide in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; 1,3,2-dioxathiolane 2,2-dioxide in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; lithium di(fluoro)(oxalato)borate in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; Lithium bis(oxalato)borate in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution; and The solution of claim 14 selected from a mixture of any two or more of these.

16. 16. The solution of claim 14 or 15, wherein the electrochemical additive is selected from 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2,2-dioxide, tris(trimethylsilyl)phosphite, lithium di(fluoro)(oxalato)borate, and lithium bis(oxalato)borate.

17. The electrochemical additives may each be 1,3-propane sultone in an amount of about 0.5 wt % to about 4 wt %, 1,3-propane sultone in an amount of about 1.5 wt % to about 12 wt %, 1,3-propene sultone in an amount of about 0.5 wt % to about 4 wt %, 1,3,2-dioxathiolane 2,2-dioxide in an amount of about 1 wt % to about 4 wt %, or 1,3,2-dioxathiolane 2,2-dioxide in an amount of about 1 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution.

15. The solution of claim 14 selected from lithium di(fluoro)(oxalato)borate in an amount of from 1% to about 4% by weight, and lithium bis(oxalato)borate in an amount of from about 1% to about 4% by weight.

18. 18. The solution of claim 16 or 17, wherein each electrochemical additive is used exclusively with other electrochemical additives.

19. 15. The solution of claim 14, wherein the electrochemical additive is selected from A) a mixture of vinylene carbonate and 1,3,2-dioxathiolane 2-oxide, B) a mixture of vinylene carbonate and 1,3-propane sultone, and C) a mixture of 1,3-propene sultone, tris(trimethylsilyl)phosphite, and 1,3,2-dioxathiolane 2,2-dioxide.

20. 20. The solution of claim 19, wherein the total amount of the electrochemical additives in each mixture is from about 0.25% to about 5% by weight, based on the total weight of the non-aqueous electrolyte solution.

21. 21. The solution of any of claims 14 to 20, wherein 4-bromomethyl-1,3-dioxolan-2-one is in an amount of about 10% by weight or more of bromine, based on the total weight of the solution.

22. 21. The solution of any one of claims 14 to 20, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate.

23. A non-aqueous lithium battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte solution according to any one of claims 14 to 22.

24. 1. A process for producing a non-aqueous electrolyte solution for a lithium battery, the process comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one, iv) a) unsaturated cyclic carbonates containing from 3 to about 6 carbon atoms; b) fluorine-containing saturated cyclic carbonates containing from 3 to about 5 carbon atoms and from 1 to about 4 fluorine atoms; c) tris(trihydrocarbylsilyl)phosphites containing from 3 to about 9 carbon atoms; d) trihydrocarbyl phosphates containing from 3 to about 12 carbon atoms; e) cyclic sultones containing from 3 to about 8 carbon atoms; f) saturated cyclic hydrocarbyl sulfites having five or six membered rings and containing from 2 to about 6 carbon atoms; g) saturated cyclic hydrocarbyl sulfates having five or six membered rings and containing from 2 to about 6 carbon atoms; h) cyclic dioxadithiopolyoxide compounds having 6-, 7-, or 8-membered rings and containing from 2 to about 6 carbon atoms; i) another lithium-containing salt, and j) at least one electrochemical additive selected from a mixture of any two or more of the foregoing.

25. 1. A process for producing a non-aqueous electrolyte solution for a lithium battery, the process comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one, iv) at least one electrochemical additive selected from vinylene carbonate, 4-fluoroethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide, lithium di(fluoro)(oxalato)borate, lithium bis(oxalato)borate, and mixtures of any two or more thereof.

26. 1. A non-aqueous electrolyte solution for a lithium battery, the solution comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one.

27. 27. The solution of claim 26, wherein the 4-bromomethyl-1,3-dioxolan-2-one is in an amount of about 10% or more by weight of bromine, based on the total weight of the solution.

28. 28. The solution of any of claims 26 to 27, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate.

29. A non-aqueous lithium battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte solution according to any one of claims 26 to 28.

30. 1. A process for producing a non-aqueous electrolyte solution for a lithium battery, the process comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) 4-bromomethyl-1,3-dioxolan-2-one.

31. 31. The process of claim 30, wherein the 4-bromomethyl-1,3-dioxolan-2-one is in an amount of about 10% or more by weight of bromine, based on the total weight of the solution.

32. 32. The process of any of claims 30 to 31, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate.

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