Flame retardant for battery electrolyte

Abstract

To provide a flame retardant that can effectively suppress the flammability of lithium-ion batteries at a reasonable cost while minimizing the impact on their electrochemical performance of lithium-ion batteries.SOLUTION: A non-aqueous electrolyte solution for lithium batteries includes i) a liquid electrolyte medium, ii) a lithium-containing salt, and iii) A) a brominated non-cyclic carbonate in which the carbon-carbon bonds are saturated, and B) a brominated cyclic carbonate having a carbonate ring with saturated carbon-carbon bonds, provided that the brominated cyclic carbonate is not 4-bromomethyl ethylene carbonate. The solution includes at least one oxygen-containing bromine-based flame retardant selected from the above brominated cyclic carbonates.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 at least one oxygen-containing brominated flame retardant, which, in the presence of the oxygen-containing brominated flame retardant(s), extinguish a fire in these non-aqueous electrolyte solutions, at least under laboratory conditions.

[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; and iii) at least one oxygen-containing brominated flame retardant selected from A) brominated acyclic carbonates having saturated carbon-carbon bonds and B) brominated cyclic carbonates having carbonate rings having saturated carbon-carbon bonds, with the proviso that the brominated cyclic carbonate is not 4-bromomethylethylene carbonate.

[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, and iii) at least one oxygen-containing bromine-based flame retardant, such as 2-bromoethyl methyl carbonate, 2,2-dibromoethyl methyl carbonate, 2,2,2-tribromoethyl methyl carbonate, bis(2-bromoethyl) carbonate, 4-bromo-1,3-dioxolan-2-one, 4,5-dibromo-1,3-dioxolan-2-one, or 4,4,5-tribromo-1,3-dioxolan-2-one. , 4,4-bis(bromomethyl)-1,3-dioxolan-2-one, 4,5-bis(bromomethyl)-1,3-dioxolan-2-one, 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, and 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

[0007] 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

[0008] Throughout this specification, the phrase "electrolyte solution" is used interchangeably with the phrase "nonaqueous electrolyte solution."

[0009] 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 include polar and aprotic solvents. , stable to electrochemical cycling, and preferably low viscosity. These solvents typically include acyclic carbonates, cyclic carbonates, ethers, sulfur-containing compounds, and esters of boric acid.

[0010] 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, ethylene sulfite, 1,3-propylene glycol borate, and mixtures of any two or more of the foregoing.

[0011] 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.

[0012] 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(oxolato)borate (LiBOB), lithium di(fluoro)(oxalato)borate, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium titanate, lithium manganate, and lithium cobaltate. Examples of suitable lithium 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.

[0013] A 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 multiple 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.

[0014] The electrolyte solution can contain other salts in addition to lithium salts, provided that such other salt(s) do not substantially degrade either the battery's performance for the desired application or the flame retardancy of the electrolyte solution. Suitable electrolytes other than lithium salts include other alkali metal salts, such as sodium salts, potassium salts, rubidium salts, and cesium salts, and alkaline earth metal salts, such as magnesium salts, calcium salts, strontium salts, and barium salts. In some embodiments, the only salt in the non-aqueous electrolyte solution is one or more lithium salts.

[0015] 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, as well as sodium salts such as potassium chloride, potassium bromide, sodium iodide, sodium perchlorate, sodium nitrate, sodium thiocyanate, sodium aluminate, sodium tetrachloroaluminate, sodium tetrafluoroaluminate, sodium tetraphenylborate, sodium tetrafluoroborate, and sodium hexafluorophosphate. Examples of suitable potassium salts include potassium iodide, potassium perchlorate, potassium nitrate, potassium thiocyanate, potassium aluminate, potassium tetrachloroaluminate, potassium tetrafluoroaluminate, potassium tetraphenylborate, potassium tetrafluoroborate, and potassium hexafluorophosphate.

[0016] 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.

[0017] In the practice of the present invention, the brominated flame retardant is miscible with the liquid medium of the non-aqueous electrolyte solution, where "miscible" means that the brominated flame retardant does not form a separate phase from the electrolyte solution. More specifically, a brominated flame retardant 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 brominated flame retardant does not precipitate from the non-aqueous electrolyte solution or form a suspension or slurry. It is recommended and preferred that the brominated flame retardant not cause precipitation of any of the other components of the non-aqueous electrolyte solution or form a suspension or slurry.

[0018] In the practice of the present invention, the oxygen-containing brominated flame retardant generally has a bromine content of about 35% by weight or more, preferably about 40% by weight or more, based on the weight of the oxygen-containing brominated flame retardant, and a boiling point of about 75° C. or more, preferably about 95° C. or more. In the practice of the present invention, the oxygen-containing brominated flame retardant has a bromine content in the molecule ranging from about 35% by weight to about 80% by weight, more preferably from about 40% by weight to about 75% by weight.

[0019] The boiling point of the brominated flame retardant of the present invention is about 75° C. or higher, preferably about 95° C. or higher, and is usually in the range of about 75° C. to about 450° C., preferably about 95° C. to about 425° C., and more preferably about 100° C. to about 410° C. Unless otherwise specified, boiling points described throughout this specification are those at standard temperature and pressure (standard conditions).

[0020] Oxygen-containing brominated flame retardants are generally polar and aprotic, stable to electrochemical cycling, and preferably have low viscosity.

[0021] In the practice of the present invention, the amount of flame retardant in the non-aqueous electrolyte solution means that there is enough flame retardant present so that the solution passes the modified horizontal UL-94 test described below. The amount of flame retardant often varies for different brominated flame retardants, but is typically about 12% by weight or more of the flame retardant molecules, preferably about 13% by weight 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 10% by weight or more of bromine (atoms), preferably about 11% by weight or more, based on the total weight of the non-aqueous electrolyte solution.

[0022] The oxygen-containing brominated flame retardants of the present invention share several general characteristics: In these brominated flame retardants, the bromine content is greater than about 35% by weight, preferably from about 35% to about 80% by weight, and more preferably from about 40% to about 75% by weight, based on the total weight of the flame retardant molecule. Typically, there are 1 to about 5 bromine atoms in the oxygen-containing brominated flame retardant molecule, preferably 1 to about 3 bromine atoms, and there are about 3 to about 10 carbon atoms in the oxygen-containing brominated flame retardant molecule, preferably about 3 to about 6 carbon atoms.

[0023] In some embodiments, the oxygen-containing brominated flame retardant is a brominated acyclic carbonate having two hydrocarbyl groups, each of which independently has 3 to about 8 carbon atoms, preferably 3 to about 6 carbon atoms, and at least one hydrocarbyl group has at least one bromine atom. The carbon-carbon bonds of the hydrocarbyl groups of the brominated acyclic carbonate are saturated. These brominated acyclic carbonates have a bromine content of about 35 wt % or more, preferably about 35 wt % to about 80 wt %, and more preferably about 40 wt % to about 75 wt %, based on the weight of the brominated acyclic carbonate. In some preferred embodiments, the brominated acyclic carbonate has about 4 to about 6 carbon atoms in the molecule, and the brominated acyclic carbonate preferably has 1 to about 4 bromine atoms in the molecule.

[0024] The hydrocarbyl group of the brominated acyclic carbonate is an alkyl group such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, and isobutyl. Preferably, the hydrocarbyl group is a methyl group or an ethyl group. In some preferred brominated acyclic carbonates, one of the hydrocarbyl groups is a methyl group. When there are two or more bromine atoms in the molecule, they may be present in one or both hydrocarbyl groups, and when one of the hydrocarbyl groups is a methyl group, the bromine atom is preferably present in the other hydrocarbyl group. Preferably, the brominated acyclic carbonate is 2-bromoethyl methyl carbonate, 2,2-dibromoethyl methyl carbonate, 2,2,2-tribromoethyl methyl carbonate, or bis(2-bromoethyl) carbonate.

[0025] In another embodiment, the oxygen-containing brominated flame retardant is a brominated cyclic carbonate. In the brominated cyclic carbonate, the carbonate group is part of a ring structure. The carbon-carbon bond of the brominated cyclic carbonate ring is saturated. In the brominated cyclic carbonate, the carbonate ring is preferably a saturated five-membered or six-membered ring, and the brominated cyclic carbonate contains at least one bromine atom. Optionally, at least one hydrocarbyl group is bonded to at least one carbon atom of the ring. The hydrocarbyl group bonded to one or more carbon atoms of the carbonate ring is a saturated or unsaturated hydrocarbyl group having from 1 to about 4 carbon atoms, such as methyl, ethyl, ethenyl, n-propyl, 2-propyl, 1-propenyl, n-butyl, isobutyl, and 2-butenyl. Preferred groups are methyl, ethyl, and ethenyl. A more preferred hydrocarbyl group is a methyl group.

[0026] Preferably, the brominated cyclic carbonate has about 3 to about 10 carbon atoms, more preferably about 3 to about 7 carbon atoms, and preferably has 1 to about 5, more preferably 1 to about 3 bromine atoms, per molecule. The brominated cyclic carbonate typically has a bromine content of 35% by weight or more, preferably about 35% by weight to about 80% by weight, more preferably about 40% by weight to about 75% by weight, based on the total weight of the molecule.

[0027] In the brominated cyclic carbonate, the bromine atoms may be bonded to carbon atoms in the ring and / or, if present, to at least one hydrocarbyl group bonded to a carbon atom in the cyclic carbonate ring. Preferably, all bromine atoms are in one or more hydrocarbyl groups, or all bromine atoms are bonded to carbon atoms in the ring. There may be multiple hydrocarbyl groups bonded to the ring of the brominated cyclic carbonate. When there are two or more bromine atoms in the brominated cyclic carbonate and two or more hydrocarbyl groups bonded to the carbonate ring, the bromine atoms may be in the same or different hydrocarbyl groups, preferably different hydrocarbyl groups.

[0028] Preferably, the brominated cyclic carbonate is 4-bromo-1,3-dioxolan-2-one, 4,5-dibromo-1,3-dioxolan-2-one, 4,4,5-tribromo-1,3-dioxolan-2-one, 4,4-bis(bromomethyl)-1,3-dioxolan-2-one, 4,5-bis(bromomethyl)-1,3-dioxolan-2-one, 4-(2-bromoethenyl)-1,3-dioxolan-2-one (1-bromovinylethylene carbonate), 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, or 5,5-bis(bromomethyl)-1,3-dioxan-2-one. More preferably, the brominated cyclic carbonate is 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

[0029] In some preferred embodiments of the present invention, 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.

[0030] In some embodiments of the present invention, at least one electrochemical additive is included in the non-aqueous electrolyte solution.

[0031] 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 with 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.

[0032] The term "soluble," as commonly used for 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 wt. % ethylene carbonate and 70 wt. % ethyl methyl carbonate containing 1.2 M lithium hexafluorophosphate and does not form a precipitate, suspension, or slurry after shaking is stopped. It is recommended and preferred that the electrochemical additive not cause precipitation of any of the other components of the non-aqueous electrolyte solution or the formation of a suspension or slurry.

[0033] Brominated flame retardants, 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 non-aqueous electrolyte solution.

[0034] 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) mixtures of any two or more of the foregoing.

[0035] In another embodiment, the electrochemical additive comprises: 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) a 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 fluorine-containing saturated cyclic carbonate in an amount of about 0.25 wt % to about 5 wt % based on the total weight of the non-aqueous electrolyte solution; f) 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; g) 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; h) 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; i) 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 j) a mixture of any two or more of the foregoing.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 phosphate can be the same or different. Suitable trihydrocarbyl phosphates include: Examples of the trihydrocarbyl phosphate include trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, tri-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 nonaqueous electrolyte solution.

[0040] 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 amount of the cyclic sultone is preferably 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.

[0041] 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.

[0042] 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.

[0043] 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. Preferably, the cyclic dioxadithiopolyoxide compound contains 2 to about 4 carbon atoms and has a 6- or 7-membered ring. One or more substituents, such as ethyl or ethyl groups, preferably one or more methyl groups, may 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 cyclic dioxadithiopolyoxide compound is preferably present in an amount of about 0.5% to about 5% by weight, more preferably about 1% to about 4% by weight, based on the total weight of the nonaqueous electrolyte solution.

[0044] 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% to about 10% by weight, preferably about 1% to about 8% by weight, 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.

[0045] A mixture of any two or more of the aforementioned electrochemical additives can be used, including different 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% by weight to about 5% 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.

[0046] Preferred types of electrochemical additives include saturated cyclic hydrocarbyl sulfates, cyclic sultones, tris(trihydrocarbylsilyl)phosphites, 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% to about 4% by weight, the cyclic sultones in an amount of about 0.5% to about 4% by weight, the tris(trihydrocarbylsilyl)phosphites in an amount of about 0.15% to about 4% by weight, and the other lithium-containing salts in an amount of about 1% to about 4% by weight, respectively, based on the total weight of the non-aqueous electrolyte solution.

[0047] In other embodiments, the electrochemical additive is selected from vinylene carbonate, 4-fluoro-ethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, ethylene sulfite, 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 mixtures of any two or more thereof. The electrochemical additive is preferably 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propane sultone, 1,3-propene sultone, tris(trimethylsilyl)phosphite, 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, or lithium bis(oxalato)borate. More preferred electrochemical additives are 1,3,2-dioxathiolane 2,2-dioxide, lithium di(fluoro)(oxalato)borate, and lithium bis(oxalato)borate. The amount and desirability thereof are as described above.

[0048] In some preferred embodiments, the electrochemical additive is vinylene carbonate in an amount of about 0.5% to about 3% by weight, based on the total weight of the non-aqueous electrolyte solution. More preferably, the flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one.

[0049] In some preferred embodiments, the cyclic sultone is 1,3-propane sultone in an amount of about 0.5 wt % to about 4 wt %, based on the total weight of the non-aqueous electrolyte solution. More preferably, the flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one.

[0050] In some preferred embodiments, the cyclic sultone is 1,3-propane sultone in an amount of about 1.5 wt % to about 10 wt %, based on the total weight of the non-aqueous electrolyte solution. More preferably, the flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one.

[0051] In some preferred embodiments, the electrochemical additive is lithium di(fluoro)(oxalato)borate in an amount of about 1% to about 10% by weight, more preferably about 1.5% to about 8% by weight, based on the total weight of the non-aqueous electrolyte solution. More preferably, the flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one.

[0052] A mixture of any two or more of the foregoing electrochemical additives can be used. When a mixture of electrochemical additives is used, the total amount of electrochemical additives is about 0.25 wt % to about 5 wt % based on the total weight of the non-aqueous electrolyte solution.

[0053] 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.

[0054] Another embodiment of the present invention provides a process for producing a non-aqueous electrolyte solution for a lithium battery. The process includes blending components including: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) at least one oxygen-containing bromine-based flame retardant. Optionally, the components further include iv) at least one electrochemical additive as described above. The oxygen-containing bromine-based flame retardant is present in the electrolyte solution in a flame-retardant amount. The components can be blended in any order, but it is preferred that all components are added to the liquid electrolyte medium. It is also preferred that optional components be added to the liquid electrolyte medium. The characteristics and preferences of the liquid electrolyte medium, the lithium-containing salt, the oxygen-containing bromine-based flame retardant, the electrochemical additive(s), and the amounts of each component are as described above.

[0055] 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) at least one oxygen-containing brominated flame retardant. The oxygen-containing brominated flame retardant is present in the electrolyte solution in a flame retardant amount. Optionally, the components further include iv) at least one electrochemical additive as described above. The brominated flame retardant may be 2-bromoethyl methyl carbonate, 2,2-dibromoethyl methyl carbonate, 2,2,2-tribromoethyl methyl carbonate, bis(2-bromoethyl) carbonate, 4-bromo-1,3-dioxolan-2-one, 4,5-dibromo-1,3-dioxolan-2-one, or 4,4,5-tribromo-1,3-dioxolan-2-one. from the group consisting of 4,4-bis(bromomethyl)-1,3-dioxolan-2-one, 4,5-bis(bromomethyl)-1,3-dioxolan-2-one, 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, and 5,5-bis(bromomethyl)-1,3-dioxan-2-one; The liquid electrolyte medium, lithium-containing salt, brominated flame retardant, electrochemical additive(s), and the amounts of each component are as described above.

[0056] The non-aqueous electrolyte solution of the present invention containing one or more brominated flame retardants 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.

[0057] The molecule 4-(2-bromoethenyl)-1,3-dioxolan-2-one is a new composition of matter.

[0058] The following examples are presented for illustrative purposes and are not intended to impose limitations on the scope of the present invention.

[0059] To determine flame retardancy, a modified horizontal UL-94 test was performed. This modified horizontal UL-94 test is very similar to the known published horizontal UL-94 test. 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 is as follows:

[0060] The core was cut from a cylindrical fiberglass core, the cut edge smoothed, and dust and particles removed from the core surface. Prior to testing, the core was dried at 120°C for 20 hours. The core length was 5 ± 0.1 in (12.7 ± 0.25 cm). Each test specimen was prepared in a 4-oz (120 mL) glass bottle in a dry box. The desired amount of flame retardant was blended with the desired amount of simple electrolyte solution. For example, 20 wt% brominated flame retardant and 80 wt% simple electrolyte solution were combined to form a flame-retardant-containing electrolyte solution. Before blending with the flame retardant, the simple electrolyte solution contained 1.2 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (3:7 weight ratio). 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 dripping occurred, and then placed in a 4-oz (120 mL) glass bottle. 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 its 4 oz (120 mL) glass bottle 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 burning 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.

[0061] If the flame was extinguished when the burner was removed, the specimen was 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."

[0062] The flame retardancy of each flame retardant is determined by performing a modified horizontal UL-94 test at least three times. went.

[0063] Example 1 The non-aqueous electrolyte solutions containing 4-(2-bromoethenyl)-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]

[0064] Example 2 Several non-aqueous electrolyte solutions containing brominated flame retardants were tested in coin cells. Coin cells were assembled using the non-aqueous electrolyte solutions containing the desired amounts of flame retardants. 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.

[0065] One sample contained 1.2 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (3:7 weight ratio) as a non-aqueous electrolyte solution without flame retardant. The remaining samples contained the desired amount of flame retardant in the electrolyte solution. The results are summarized in Tables 2A and 2B below. The margin of error for coulombic efficiency is approximately ±0.5% to approximately ±1.0%. The results reported in Table 2A are the average of multiple cells unless otherwise noted. "Multiple cells" typically refers to two or three cells. The results reported in Table 2B are for the best-performing single cell. [Table 2] 1 Comparison carried out. 2 Data is for the best performing single cell. 3 To increase the overall conductivity of the electrolyte, additional LiPF salt was added to the 4-(2-bromoethenyl)-1,3-dioxolan-2-one flame retardant. The total effective concentration of LiPF in the flame retardant-containing electrolyte solution was 1.1 M before adding the additive.

[0066] Some flame retardants were tested in coin cells up to 100 cycles, and the results are reported in Table 2B below. The data for each flame retardant below are reported from the best performing single cell. [Table 3] 1 Comparison 2 To increase the overall conductivity of the electrolyte, additional LiPF salt was added to the 4-(2-bromoethenyl)-1,3-dioxolan-2-one flame retardant. The total effective concentration of LiPF in the flame retardant-containing electrolyte solution was 1.1 M before adding the additive.

[0067] Example 3 Synthesis of 4-(2-bromoethenyl)-1,3-dioxolan-2-one Dichloromethane (100 mL) and 4-ethenyl-1,3-dioxolan-2-one (22.8 g, 0.2 mol) were placed in a 250 mL round-bottom flask and magnetically stirred in an ice-cold water bath. To this mixture, Br2 (32 g, 0.2 mol) was slowly added using a peristaltic pump. After all the Br2 was added, the reaction mixture was allowed to cool to room temperature while stirring for 2 minutes. The mixture was stirred for 1 hour. The reaction flask was then placed in an ice-water bath, and triethylamine (22.3 g, 0.22 mol) was added dropwise through the addition funnel to the flask. After all the triethylamine was added, the reaction mixture was stirred for 4 hours while the reaction mixture was allowed to return to room temperature. The mixture was filtered to remove any solids that had formed, and the remaining liquid was collected in a 250 mL round-bottom flask. After the solvent was removed from the remaining liquid in the round-bottom flask, the remaining liquid in the round-bottom flask was passed through a silica gel column and purified by vacuum distillation to give 4-(2-bromoethenyl)-1,3-dioxolan-2-one (19.6 g, 50.8% yield).

[0068] 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.

[0069] The present invention may comprise, consist of, or consist essentially of the materials and / or procedures recited herein.

[0070] As used herein, the term "about" modifying the amount of a component in a composition or used in a method of the present invention refers to variations in numerical quantity that may occur, for example, due to typical measurements and liquid handling procedures used in making concentrates or using solutions in the real world; due to inadvertent errors in these procedures; due to differences in the manufacture, source, or purity of components used to make the composition or carry out the method; etc. The term about also encompasses amounts that differ due to different equilibrium conditions of a composition resulting from a particular initial mixture. Whether modified by the term "about," the claims encompass the equivalent of the quantity.

[0071] 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.

[0072] 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; iii) A) a brominated acyclic carbonate in which the carbon-carbon bonds are saturated, and B) a brominated cyclic carbonate having a carbonate ring in which the carbon-carbon bond is saturated, with the proviso that the brominated cyclic carbonate is not 4-bromomethylethylene carbonate.

2. 10. The solution of claim 1, wherein the oxygen-containing brominated flame retardant has about 3 to about 10 carbon atoms, 1 to about 5 bromine atoms, and / or a bromine content of about 35 wt.% or greater, based on the total weight of the oxygen-containing brominated flame retardant.

3. The oxygen-containing bromine-based flame retardant is a brominated acyclic carbonate having from about 4 to about 8 carbon atoms and from 1 to about 4 bromine atoms, or 2. The solution of claim 1, which is a brominated cyclic carbonate having from about 3 to about 8 carbon atoms, from 1 to about 4 bromine atoms, and having a bromine content of at least about 35 wt. % based on the total weight of the oxygen-containing brominated flame retardant.

4. The oxygen-containing bromine-based flame retardant is brominated acyclic carbonates, or 4. The solution of claim 1, which is a brominated cyclic carbonate containing two or more bromine atoms, either all in one or more hydrocarbyl groups attached to the carbonate ring, or all of the bromine atoms are attached to carbon atoms of the carbonate ring.

5. The oxygen-containing bromine-based flame retardant is brominated acyclic carbonates having hydrocarbyl groups selected from methyl and ethyl groups, or 5. The solution of claim 4, which is a brominated cyclic carbonate containing two or more bromine atoms and having two or more hydrocarbyl groups attached to the carbonate ring, wherein the bromine atoms are in different hydrocarbyl groups.

6. 6. The solution of claim 1 or 5, wherein the oxygen-containing brominated flame retardant is a brominated acyclic carbonate in which one hydrocarbyl group is a methyl group.

7. 6. The solution according to claim 1, wherein the oxygen-containing brominated flame retardant is a brominated cyclic carbonate having two or more hydrocarbyl groups attached to the carbonate ring, and the hydrocarbyl groups are methyl groups.

8. 10. The solution of claim 1, wherein the oxygen-containing brominated flame retardant is a brominated cyclic carbonate having a 5- or 6-membered ring, optionally having from about 3 to about 8 carbon atoms, from 1 to about 5 bromine atoms, and / or having a bromine content of about 35 wt. % or greater, based on the total weight of the oxygen-containing brominated flame retardant.

9. The oxygen-containing bromine-based flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, or The solution of claim 1, which is 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

10. 10. The solution of claim 1, wherein the brominated flame retardant has a boiling point of about 95°C or greater.

11. 10. The solution of claim 1, wherein the brominated flame retardant has a boiling point in the range of about 75°C to about 450°C.

12. 12. The solution of claim 1, wherein the oxygen-containing brominated flame retardant is present in an amount of about 10% by weight or more of bromine, based on the total weight of the solution.

13. 13. The solution of any of claims 1 to 12, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate.

14. 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) a mixture of any two or more of the foregoing.

15. 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.

16. 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 sultone in an amount of about 0.25 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; f) a saturated cyclic hydrocarbyl sulfite in an amount of about 0.5 wt % to about 5 wt %, based on the total weight of the non-aqueous electrolyte solution; g) 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; h) 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; i) 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.

17. 17. The solution of any of claims 14 to 16, wherein the electrochemical additive is a saturated cyclic hydrocarbyl sulfate, a cyclic sultone, a tris(trihydrocarbylsilyl)phosphite, or another lithium-containing salt.

18. 15. The solution of claim 14, wherein the electrochemical additive is an unsaturated cyclic carbonate in an amount of about 0.5 wt % to about 3 wt %, 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 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.

19. 19. The solution of claim 18, wherein the electrochemical additive is vinylene carbonate, 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.

20. 20. The solution of claim 18 or 19, wherein each electrochemical additive is used exclusively with other electrochemical additives.

21. 17. The solution of any one of claims 14 to 16, wherein the electrochemical additive is selected from vinylene carbonate, 4-fluoro-ethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1,3-propane sultone, 1,3-propene sultone, ethylene sulfite, 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.

22. 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 10 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 10 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 22. The solution of claim 21, selected from the group consisting of:

23. 23. The solution of claim 21 or 22, wherein the electrochemical additive is selected from vinylene carbonate, 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.

24. 22. The solution of claim 21 , wherein the electrochemical additive is selected from vinylene carbonate in an amount of about 0.5 wt % to about 3 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 10 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 %, lithium di(fluoro)(oxalato)borate in an amount of about 1 wt % to about 10 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 %, each based on the total weight of the non-aqueous electrolyte solution.

25. The solution of claim 23 or 24, wherein the flame retardant comprises 4-(2-bromoethenyl)-1,3-dioxolan-2-one.

26. 25. The solution of claim 23 or 24, wherein each electrochemical additive is used exclusively with other electrochemical additives.

27. 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 26.

28. 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) 2-bromoethyl methyl carbonate, 2,2-dibromoethyl methyl carbonate, 2,2,2-tribromoethyl methyl carbonate, bis(2-bromoethyl)carbonate, 4-bromo-1,3-dioxolan-2-one, 4,5-dibromo-1,3-dioxolan-2-one, 4,4,5-tribromo-1,3-dioxolan-2-one, 4,4-bis(bromomethyl)-1,3 and at least one oxygen-containing bromine-based flame retardant selected from the group consisting of 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 4,5-bis(bromomethyl)-1,3-dioxolan-2-one, 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, and 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

29. 29. The solution of claim 28, wherein the oxygen-containing brominated flame retardant is 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, or 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

30. 30. The solution of any one of claims 28 to 29, wherein the oxygen-containing brominated flame retardant is in an amount of about 10% by weight or more of bromine, based on the total weight of the solution.

31. 30. The solution of any of claims 28 to 29, wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and / or the lithium-containing salt is lithium hexafluorophosphate, lithium di(fluoro)(oxalato)borate, or lithium bis(oxalato)borate.

32. A non-aqueous lithium battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte solution of any one of claims 28 to 31.

33. 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; iii) A) a brominated acyclic carbonate in which the carbon-carbon bonds are saturated, and B) a brominated cyclic carbonate having a carbonate ring in which the carbon-carbon bond is saturated, with the proviso that the brominated cyclic carbonate is not 4-bromomethylethylene carbonate.

34. The components are 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) a mixture of any two or more of the foregoing.

35. 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) 2-bromoethyl methyl carbonate, 2,2-dibromoethyl methyl carbonate, 2,2,2-tribromoethyl methyl carbonate, bis(2-bromoethyl)carbonate, 4-bromo-1,3-dioxolan-2-one, 4,5-dibromo-1,3-dioxolan-2-one, 4,4,5-tribromo-1,3-dioxolan-2-one, 4,4-bis(bromomethyl)-1,3-dioxolane and at least one oxygen-containing brominated flame retardant selected from the group consisting of 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 4,5-bis(bromomethyl)-1,3-dioxolan-2-one, 4-(2-bromoethenyl)-1,3-dioxolan-2-one, 5-(bromomethyl)-5-methyl-1,3-dioxan-2-one, and 5,5-bis(bromomethyl)-1,3-dioxan-2-one.

36. 36. The process of claim 35, wherein the components further comprise 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, ethylene sulfite, 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.

37. 4-(2-Bromoethenyl)-1,3-dioxolan-2-one.

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