Electrolytes with low sulfamate ion content

Abstract

The present invention relates to - an ionic liquid, comprising: · bis(fluorosulfonyl)imide anion, · a phosphonium cation of formula (PR 1 R 2 R 3 R 4 ) + (wherein each R 1 , R 2 , R 3 and R 4 group independently represents a saturated or unsaturated linear or branched alkyl group containing 1 to 14 carbon atoms, an alkyl-aryl group containing 7 to 14 carbon atoms, or an aryl group containing 6 to 10 carbon atoms, and R 1 , R 2 , R 3 and R 4 groups can optionally contain one or more heteroatoms) an ionic liquid comprising; and - lithium bis(fluorosulfonyl)imide salt The present invention relates to an electrolyte, wherein the content of sulfamate ions is 0.1 to 3000 ppm by weight.

Description

[Technical Field]

[0001] The present invention relates to an electrolyte comprising a lithium bis(fluorosulfonyl)imide (LiFSI) salt and an ionic liquid containing a bis(fluorosulfonyl)imide (FSI) anion and a phosphonium cation, exhibiting a low content of sulfamate ions; as well as a method for preparing this electrolyte, an electrochemical cell containing this electrolyte, and a battery containing such an electrochemical cell. [Background technology]

[0002] Lithium (Li) batteries, such as lithium-ion batteries, are commonly used in electric vehicles, mobile devices, and portable devices.

[0003] A lithium-ion battery comprises at least a negative electrode (anode), a positive electrode (cathode), an electrolyte, and preferably a separator. The electrolyte consists of a lithium salt dissolved in a solvent, which is generally a mixture of organic solvents, in order to obtain a good balance between the viscosity and dielectric constant of the electrolyte.

[0004] Adding additives can improve the stability of the electrolyte salt or passivation layer. This is because the passivation layer formed during the battery's first charge-discharge cycle is essential for battery life. Examples of passivation layers include the aluminum passivation, commonly used as a current collector in the cathode, and the solid electrolyte interface (SEI), which consists of both inorganic and polymeric layers formed at the anode / electrolyte interface and the cathode / electrolyte interface. The stability of these interfaces is a major challenge in improving battery life.

[0005] Another major challenge is improving the overall safety of batteries, particularly for electric vehicle applications. This is because the flammability of the solvents used in the electrolyte is a concern. Various solutions exist to avoid the flammability of the electrolyte, such as the use of fluorinated solvents or ionic liquids.

[0006] The use of fluorinated solvents has the disadvantage of reducing the ionic conductivity of the electrolyte. While ionic liquids do not exhibit this drawback, a considerable amount of ionic liquid is required to make the electrolyte non-flammable. Under these conditions, using an ionic liquid that exhibits good electrochemical stability is essential to obtain a battery with a satisfactory lifespan.

[0007] Furthermore, lithium-ion batteries with silicon anodes or silicon-graphite anodes have high theoretical capacity (up to 10 times that of graphite). However, the large volume changes (up to 300%) that occur during lithium insertion and removal place significant stress on the electrodes, exposing the silicon particles to constant SEI regeneration and continuous electrolyte degradation.

[0008] References EP2162942, EP2549577, WO2018 / 172696, WO2019 / 113406, US10446875, EP3503268, and the paper by G. Girard et al. (Phys.Chem.Chem.Phys., 2015, 17, 8706-8713) describe various ionic liquids containing anions such as FSI and their use in batteries. Reference WO2016 / 049391 describes ionic liquids in other applications.

[0009] As taught in references WO99 / 40025, US2009 / 0270286, WO2018 / 172696 and US2021 / 0194059, it is known to produce ionic liquids containing FSI anions starting from potassium bis(fluorosulfonyl)imide (KFSI).

[0010] Reference WO2020 / 241161 describes electrolytes containing sulfonylimid compounds and amide sulfuric acid compounds.

[0011] Reference WO2019 / 229359 describes a method for producing salts such as LiFSI starting from bis(fluorosulfonyl)imide (HFSI).

[0012] Document EP3954651 describes an aqueous LiFSI composition.

[0013] A paper by K. Arano et al. (Journal of the Electrochemical Society, 2020, 167(12), 120520) relates to the electrochemical behavior of silicon in two types of ionic liquids including a phosphonium-based ionic liquid.

[0014] A paper by K. Arano et al. (ACS Applied Materials & Interfaces, 2021, 13(24), 28281-28294) describes characterization of SEI on silicon anodes as a function of the cation of the ionic liquid and the concentration of LiFSI in the electrolyte.

[0015] There is a need to provide a more efficient electrolyte that forms a more stable SEI and improves battery life, particularly when used in electrochemical cells having a silicon-containing anode. Summary of the Invention

[0016] The present invention firstly provides: - an ionic liquid, comprising: - bis(fluorosulfonyl)imide anion, - at least one phosphonium cation of formula (PR 1 R 2 R 3 R 4 ) + (wherein each R 1 , R 2 , R 3 and R 4 groups each independently represent a saturated or unsaturated linear or branched alkyl group containing 1 to 14 carbon atoms, or an alkyl-aryl group containing 7 to 14 carbon atoms, or an aryl group containing 6 to 10 carbon atoms, R 1 , R 2 , R 3 and R 4 groups may optionally contain one or more heteroatoms) Ionic liquids containing; and - Lithium bis(fluorosulfonyl)imide salt This relates to an electrolyte containing a sulfamate ion content ranging from 0.1 to 3000 ppm by weight.

[0017] In some embodiments, the phosphonium cation is tetraethylphosphonium, tetrabutylphosphonium, trimethyl(propyl)phosphonium, trimethyl(hexyl)phosphonium, trimethyl(2-methylpropyl)phosphonium, triethyl(methyl)phosphonium, triethyl(butyl)phosphonium, triethyl(pentyl)phosphonium, triethyl(hexyl)phosphonium, tributyl(methyl)phosphonium, tri(2-methylpropyl)(methyl)phosphonium, trihexyl(dodecyl)phosphonium, trihexyl(tetradecyl)phosphonium, dimethyldipropylphosphonium, diethyl(methyl)(2-methylpropyl You can choose from phosphonium (Pyrophosphonium), tributyl(6-hepten-1-yl)phosphonium, tetraphenylphosphonium, triphenyl(methyl)phosphonium, trimethyl(methoxymethyl)phosphonium, triethyl(methoxymethyl)phosphonium, triethyl(2-methoxyethyl)phosphonium, triethyl[(methylthio)methyl]phosphonium, triethyl[2-(methylthio)ethyl]phosphonium, triethyl[2-(ethylthio)ethyl]phosphonium, tributyl[(methylthio)methyl]phosphonium, tributyl[2-(methylthio)ethyl]phosphonium, and tributyl[2-(ethylthio)ethyl]phosphonium.

[0018] In some embodiments, the sulfamate ion content may be 1 to 1000 ppm by weight, preferably 10 to 300 ppm.

[0019] In some embodiments, the ionic liquid can be present in a weight content of 1% to 90%, preferably 20% to 80%.

[0020] In some embodiments, the electrolyte may include at least one organic solvent.

[0021] In some embodiments, the lithium bis(fluorosulfonyl)imide salt can be present at a concentration of 0.1 M to 6 M, preferably 0.2 M to 4 M, relative to the total of the ionic liquid and optionally present organic solvents.

[0022] The present invention also relates to a method for preparing the above-mentioned electrolyte, comprising the step of mixing a lithium bis(fluorosulfonyl)imide salt with an ionic liquid.

[0023] In some embodiments, the ionic liquid is - Providing bis(fluorosulfonyl)imide compounds; and - Reaction of bis(fluorosulfonyl)imide with phosphonium cation precursor It is prepared by [method].

[0024] In some embodiments, the bis(fluorosulfonyl)imide exhibits a sulfamic acid content of 1 to 5000 ppm by weight, preferably 500 to 2500 ppm.

[0025] In some embodiments, the phosphonium cation precursor is a halogenated phosphonium cation, preferably a chloride or bromide of a phosphonium cation.

[0026] In some embodiments, the reaction is - Without using organic solvents, and optionally in the presence of water; and / or - In a molar ratio of bis(fluorosulfonyl)imide / onium cation precursor of 0.9 to 1.1, preferably 1 to 1.05, more preferably 1 to 1.01; and / or - At temperatures between 10°C and 100°C, preferably between 20°C and 30°C. It will be implemented.

[0027] In some embodiments, this method - After the reaction, the reaction mixture is purified, preferably by washing, sedimentation, and / or drying. Includes.

[0028] The present invention also relates to an electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte, wherein the electrolyte is as described above.

[0029] In some embodiments, the negative electrode comprises an electrochemically active material containing silicon in a weight content of preferably 10% or more, more preferably 20% or more.

[0030] The present invention also relates to a battery comprising at least one electrochemical cell as described above.

[0031] The present invention makes it possible to satisfy the needs described above. More specifically, it provides a more efficient electrolyte that results in a more stable SEI and improves battery life, especially when used in electrochemical cells having a silicon-containing anode. This is obtained by combining a LiFSI salt with a phosphonium-FSI type ionic liquid having a sulfamate ion content ranging from 0.1 to 3000 ppm by weight.

[0032] Advantageously, ionic liquids can be manufactured by relatively inexpensive methods. Advantageously, ionic liquids are expensive, K + or Li + It is produced without ion exchange, starting with reactants such as KFSI or LiFSI that may cause contamination by cations. Advantageously, the purification process of the ionic liquid is simplified compared to conventional techniques.

[0033] Advantageously, the electrolyte of the present invention makes it possible to improve the Coulomb efficiency after SEI formation and extend the battery life (i.e., increase the number of cycles in which at least 80% of the battery's initial capacity can be maintained), especially in the presence of a silicon-containing anode.

[0034] Advantageously, batteries incorporating this electrolyte exhibit increased safety (due to their low flammability) and good performance quality even at high charge-discharge rates. [Modes for carrying out the invention]

[0035] The present invention will be described in more detail and without limitation in the following description.

[0036] Unless otherwise specified, all percentages and proportions are weight percentages and weight proportions, and all ratios between two quantities are weight ratios.

[0037] [Ionic liquid] The ionic liquid present in the electrolyte of the present invention is bis(fluorosulfonyl)imide or formula N(SO2F)2) - The FSI anion and formula (PR 1 R 2 R 3 R 4 ) + It contains a phosphonium cation.

[0038] An ionic liquid is a salt having a melting point below 100°C, preferably below ambient temperature (i.e., below a temperature range of 15°C to 35°C). Therefore, the term "ionic liquid" is understood to mean a salt, i.e., an ionic compound containing at least anions and cations, that exists in a liquid state at a temperature of 100°C. Ionic liquids contain only ionic substances (cations and anions), with the possibility of nonionic impurities.

[0039] Therefore, the ionic liquid contains at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight, more preferably at least 99% by weight, even more preferably at least 99.5% by weight, and even more preferably at least 99.9% by weight or more of FSI anions and phosphonium cations.

[0040] In a given embodiment, several types of phosphonium cations may be present, but preferably only one type of phosphonium cation is present. In this specification, when a singular phosphonium cation is referred to, if several types are present, it should be interpreted as referring to all of the phosphonium cations.

[0041] In some embodiments, the ionic liquid may contain one or more other anions and / or one or more other cations.

[0042] In some embodiments, the ionic liquid contains FSI anions in addition to F - Cl - , Br - , I - NO3 - , M(R 1 )4 - , A(R 1 )6 - , R 2 O2 - [R 2 ONZ 1 ] - [R 2 YOCZ 2 Z 3 ] - , 4,5-dicyano-1,2,3-triazolate, 3,5-bis(R F It may contain at least one other anion selected from )-1,2,4-triazolate, tricyanomethanide, pentacyanocyclopentadienide, and pentakis(trifluoromethyl)cyclopentadienide, where, - M is B, Al, Ga, or Bi; - A is P, As, or Sb; - R 1 It is a halogen; - R 2This represents an H, F, alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl, alkenylaryl, dialkylamino, alkoxy, or thioalkoxy group, each having 1 to 18 carbon atoms, being unsubstituted or substituted with one or more oxa, thia, or aza substituents, with one or more hydrogen atoms optionally substituted with halogens in proportions from 0% to 100%, and optionally forming part of a polymer chain; - Y is C, SO, S=NCN, S=C(CN)2, POR 2 P(NCN)R 2 P(C(CN)2)R 2 , alkyl, alkenyl, aryl, arylalkyl, alkylaryl, arylalkenyl, or alkenylaryl group having 1 to 18 carbon atoms and optionally substituted with one or more oxa, thia, or aza substituents; or dialkylamino N(R 1 ) 2 Represents the base; - Z 1 From Z 3 R is independent 2 , R 2 Representing YO or CN, this group optionally forms part of the polymer chain; - R F This is a perfluoro or partially fluorinated alkyl chain containing 1 to 8 carbon atoms, or a phenyl, substituted phenyl, pyridyl, or substituted pyridyl group.

[0043] General formula of phosphonium cation (PR 1 R 2 R 3 R 4 ) + In each R 1 , R 2 , R 3 and R 4 The group independently represents a saturated or unsaturated linear or branched alkyl group containing 1 to 14 carbon atoms, or an alkyl-aryl group containing 7 to 14 carbon atoms, or an aryl group containing 6 to 10 carbon atoms, R 1 , R 2 , R 3and R 4 The group can optionally contain one or more heteroatoms.

[0044] Preferred alkyl groups are those containing 1 to 12 carbon atoms, particularly 1 to 6 carbon atoms.

[0045] The heteroatoms, if present, can be selected from O, N, S, P, and Si, preferably from O and S.

[0046] R 1 , R 2 , R 3 and R 4 The group can be selected from the group consisting of methyl, ethyl, propyl, 2-methylpropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, phenyl, methoxymethyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, methylthiomethyl, 2-methylthioethyl, ethylthiomethyl, 2-ethylthioethyl, and alkenyl, particularly the heptenyl group.

[0047] In a given embodiment, R 1 , R 2 , R 3 , and R 4 At least two of the groups are identical.

[0048] In a given embodiment, R 1 , R 2 , R 3 , and R 4 At least three of these groups are identical. Preferably, these at least three identical groups are selected from alkyl groups and phenyl groups, each containing 1 to 6 carbon atoms.

[0049] The preferred phosphonium cations are as follows: tetraethylphosphonium, tetrabutylphosphonium, trimethyl(propyl)phosphonium, trimethyl(hexyl)phosphonium, trimethyl(2-methylpropyl)phosphonium, triethyl(methyl)phosphonium, triethyl(butyl)phosphonium, triethyl(pentyl)phosphonium, triethyl(hexyl)phosphonium, tributyl(methyl)phosphonium, tri(2-methylpropyl)(methyl)phosphonium, trihexyl(dodecyl)phosphonium, trihexyl(tetradecyl)phosphonium, dimethyldipropylphosphonium, diethyl(methyl)(2-methyl (Tylpropyl)phosphonium, tributyl(6-hepten-1-yl)phosphonium, tetraphenylphosphonium, triphenyl(methyl)phosphonium, trimethyl(methoxymethyl)phosphonium, triethyl(methoxymethyl)phosphonium, triethyl(2-methoxyethyl)phosphonium, triethyl[(methylthio)methyl]phosphonium, triethyl[2-(methylthio)ethyl]phosphonium, triethyl[2-(ethylthio)ethyl]phosphonium, tributyl[(methylthio)methyl]phosphonium, tributyl[2-(methylthio)ethyl]phosphonium, and tributyl[2-(ethylthio)ethyl]phosphonium.

[0050] [Electrolyte] The electrolyte of the present invention comprises the above-described ionic liquid and LiFSI salt. This electrolyte may optionally further comprise one or more additional lithium salts, one or more organic solvents, one or more polar polymers, and / or one or more additives. In a given embodiment, the electrolyte essentially consists of, and indeed even consists only of, the ionic liquid, LiFSI salt, additional lithium salt (optionally), organic solvent (optionally), and additive (optionally).

[0051] Advantageously, the ionic liquid is present in the electrolyte in an amount of 1% to 90% by weight, preferably 20% to 80% by weight, and more preferably 40% to 80% by weight, relative to the total weight of the electrolyte. In some embodiments, the electrolyte may contain 1% to 10%, or 10% to 20%, or 20% to 30%, or 30% to 40%, or 40% to 50%, or 50% to 60%, or 60% to 70%, or 70% to 80%, or 80% to 90% by weight (relative to the total weight of the electrolyte) of the ionic liquid.

[0052] The LiFSI salt is present in the electrolyte at a concentration of 0.1 M to 6 M, preferably 0.2 M to 4 M, relative to the total of the ionic liquid and the organic solvent (if present). In some embodiments, the concentration of the LiFSI salt in the electrolyte may be 0.1 M to 0.2 M, or 0.2 M to 0.5 M, or 0.5 M to 1 M, or 1 M to 2 M, or 2 M to 3 M, or 3 M to 4 M, or 4 M to 5 M, or 5 M to 6 M.

[0053] The organic solvent is preferably an aprotic solvent.

[0054] Organic solvents may be selected from the following non-exclusive list: ethers, carbonate esters, cyclic carbonate esters, aliphatic carboxylic acid esters, aromatic carboxylic acid esters, cyclic esters, fluorinated solvents (especially fluorinated ethers, fluorinated esters, fluorinated orthoformates, fluorinated carbonate esters, fluorinated phosphate esters, fluorinated phosphite esters, fluorinated sulfuric acid esters), phosphate esters, nitriles, amides, sulfur compounds, alcohols, sulfoxides, and mixtures thereof.

[0055] Examples of ethers include linear or cyclic ethers, such as ethylene glycol dimethyl ether (1,2-dimethoxyethane or DME), ethylene glycol diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2,6-dimethyltetrahydrofuran, tetrahydropyran, crown ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,4-dioxane, and 1,3-dioxolane.

[0056] Examples of carbonate esters include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, diphenyl carbonate, and methylphenyl carbonate.

[0057] Examples of cyclic carbonate esters include ethylene carbonate, propylene carbonate, 2,3-dimethylethylene carbonate, butylene carbonate, vinylene carbonate, and 2-vinylethylene carbonate.

[0058] Examples of aliphatic carboxylic acid esters include methyl formate, methyl acetate, methyl propionate, ethyl acetate, propyl acetate, butyl acetate, and amyl acetate.

[0059] Examples of aromatic carboxylic acid esters include methyl benzoate and ethyl benzoate.

[0060] Examples of cyclic esters include γ-butyrolactone, γ-valerolactone, and δ-valerolactone.

[0061] Examples of fluorinated solvents include 1,1,2,2-tetrafluoroethyl methyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, hexafluoroisopropyl methyl ether, 1,1,3,3,3-pentafluoro-2-trifluoromethylpropyl methyl ether, 1,1,2,3,3,3-hexafluoropropyl methyl ether, 1 1,2,3,3,3-Hexafluoropropyl ethyl ether, 1,1,1,3,3,3-Hexafluoro-2-(2,2,2-trifluoroethoxy)propane, bis(2,2,2-trifluoroethyl) ether, 1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether, Methoxynonanafluorobutane, Ethoxynonanafluorobutane, 1,2-Bis(1,1,2,2-tetrafluoroethoxy)ethane, 2,2,3,3-Tetrafluoro-1,4-Dimethoxybutane, 2-(2-ethoxyethyl) -1,1,1-trifluoroethane, 2-(2-(2,2-difluoroethoxy)ethoxy)-1,1-difluoroethane, 2-(2-(2,2-difluoroethoxy)ethoxy)-1,1,1-trifluoroethane, 1,1,1-trifluoro-2-(2-(2,2,2-trifluoroethoxy)ethoxy)ethane, 2,2-difluoroethyl acetate, 2,2,2-trifluoroethyl acetate, 2,2-difluoroethyl propionate, 3,3-difluoropropyl acetate, 3,3-difluoropropylpropionate Onate, ethyl 4,4-difluorobutanoate, difluoroethyl formate, trifluoroethyl formate, 2,2,2-trifluoroethyl orthoformate, 4-fluoro-1,3-dioxolan-2-one (F1EC), 4,5-difluoro-1,3-dioxolan-2-one (F2EC), ethyl 1-fluoroethyl carbonate (F1DEC), 1-fluoroethyl 2,2,2-trifluoroethyl carbonate (F4DEC), bis(2,2,2-trifluoroethyl) carbonate (BFEC), 2,2,Examples include 2-trifluoroethyl methyl carbonate (F3EMC), trifluoropropylene carbonate, monofluorodimethyl carbonate, methyl 2,2,2-trifluoroethyl carbonate, 2,2-difluoroethyl methyl carbonate, trifluoroethyl ethyl carbonate, hexafluoroisopropyl methyl carbonate, ethylhexafluoroisopropyl carbonate, bis(trifluoroethyl) carbonate, and propyltrifluoroethyl carbonate.

[0062] Examples of phosphate esters include trimethyl phosphate, ethyldimethyl phosphate, diethylmethyl phosphate, and triethyl phosphate.

[0063] Examples of nitriles include acetonitrile, propionitrile, methoxypropionitrile, glutaronitrile, adiponitrile, 2-methylglutaronitrile, valeronitrile, butyronitrile, and isobutyronitrile; as well as aromatic nitriles, such as benzonitrile and tolnitrile, nitromethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, and 3-methyl-2-oxazolidinone.

[0064] Examples of amides include N-methylformamide, N-ethylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidinone, and N-vinylpyrrolidone.

[0065] Examples of sulfur compounds include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane.

[0066] Examples of alcohols include ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether.

[0067] Examples of sulfoxides include dimethyl sulfoxide, methyl ethyl sulfoxide, and diethyl sulfoxide.

[0068] All of these solvents, as described individually, can be used alone or in combination.

[0069] The content of organic solvents in the electrolyte can range from 10% to 99% by weight.

[0070] As shown above, the electrolyte may also optionally contain one or more additional lithium salts different from LiFSI. As a non-limiting example, the additional lithium salts can be selected from LiPF6 (lithium hexafluorophosphate), LiTDI (lithium 2-trifluoromethyl-4,5-dicyanoimidazolate), bis(trifluoromethanesulfonyl)imide lithium (LiTFSI), (fluorosulfonyl)(trifluoromethanesulfonyl)imide lithium (LiFTFSI), LiPOF2, lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LiB(C2O4)2), lithium difluoro(oxalato)borate (LIF2B(C2O4)), lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, lithium tris(oxalato)phosphate, LiBF4, LiNO3, and LiClO4.

[0071] The total content of additional lithium salts in the electrolyte is preferably 1.5 M or less, more preferably 0.5 M or less. This content may be particularly between 0.05 M and 1.5 M, or between 0.1 M and 1 M, or between 0.2 M and 0.5 M.

[0072] The electrolyte may optionally contain one or more polar polymers. The polar polymers preferably include monomer units derived from ethylene oxide, propylene oxide, epichlorohydrin, epifluorohydrin, trifluoroepoxypropane, acrylonitrile, methacrylonitrile, esters and amides of acrylic and methacrylic acids, vinylidene fluoride, N-methylpyrrolidone, and / or polycationic or polyanionic polymer electrolytes. If the electrolyte contains more than one polymer, at least one of them may be crosslinked.

[0073] The electrolyte may optionally contain one or more additives. These additives include nitrogen compounds such as pentafluorophenyl isocyanate (PFPS) or dimethylacrylamide (DMAA), 4-vinyl-1,3-dioxolan-2-one, pyridazine, vinylpyridazine, quinoline, vinylquinoline, butadiene, sebaconitrile, alkyl disulfides, fluorotoluene, 1,4-dimethoxytetrafluorotoluene, t-butylphenol, di(t-butyl)phenol, borane compounds such as tris(pentafluorophenyl)borane or lithium fluoromalonato(difluoro)borate, oximes, aliphatic epoxides, halogenated biphenyls, methacrylic acid, allyl ethyl carbonate, vinyl acetate, and divinyl ammonium compounds. The group can be selected from phosphates, sulfur compounds such as propanesultone (PS), prop-1-ene-1,3-sultone (PES), ethylene sulfite, butanesultone, methylmethanesulfonate, sulfone, or also 1,3-propanediol cyclic sulfate, acrylonitrile, 2-vinylpyridine, maleic anhydride, methyl cinnamate, anhydrides such as succinic anhydride, phosphonates, silane compounds such as monomethoxytrimethylsilane, dimethoxydimethylsilane, trimethoxymethylsilane (TMMS), vinyltris(2-methoxyethoxy)silane (VTMS), or other silane compounds containing vinyl, and / or 2-cyanofurans.

[0074] The total content of additives in the electrolyte is preferably 10% by weight or less, and more preferably 5% by weight or less, relative to the total weight of the electrolyte composition. This content can be particularly 0.1% to 10%, or 0.2% to 5%, or 0.5% to 2% by weight.

[0075] The electrolytes are sulfamate ions (NH2SO3) in concentrations of 3000 ppm or less; 2000 ppm or less; 1000 ppm or less; 500 ppm or less; 300 ppm or less; 200 ppm or less; 100 ppm or less; 50 ppm or less; and 20 ppm or less (by weight). - ) May contain a certain amount.

[0076] The electrolyte may contain sulfamate ions in particular 0.1 to 3000 ppm, preferably 0.5 to 2000 ppm, more preferably 1 to 1000 ppm, and more preferably 10 to 300 ppm (by weight).

[0077] The electrolyte according to the present invention may contain sulfamate ions in particular in the following amounts by weight: 0.1 to 10 ppm; 10 to 50 ppm; 50 to 100 ppm; 100 to 200 ppm; 200 to 300 ppm; 300 to 500 ppm; 500 to 1000 ppm; 1000 to 2000 ppm; and 2000 to 3000 ppm.

[0078] The sulfamate ion content shown above makes it possible to obtain optimal electrolyte performance quality.

[0079] Advantageously, the electrolyte is F in an amount of 500 ppm or less by weight, preferably 200 ppm or less, preferably 100 ppm or less, and in specified cases 50 ppm or less or 20 ppm or less. - Contains ions. F - Ions may be essentially absent, or they may be present in amounts of 0.1 ppm, 1 ppm, 2 ppm, 5 ppm, or 10 ppm or more by weight. For example, F - Ions may be present in amounts ranging from 0.1 to 500 ppm by weight, or 1 to 200 ppm, or 2 to 100 ppm, or 5 to 50 ppm, or 10 to 20 ppm.

[0080] Advantageously, the electrolyte contains Cl in an amount of 500ppm or less by weight, preferably 200ppm or less, more preferably 100ppm or less, and in certain cases 50ppm or less or 20ppm or less - ions. Cl - ions may be substantially absent, or may be present in an amount of 0.1ppm, 1ppm, 2ppm, 5ppm or 10ppm or more by weight. For example, Cl - ions may be present in an amount of 0.1 to 500ppm, or 1 to 200ppm, or 2 to 100ppm, or 5 to 50ppm, or 10 to 20ppm by weight.

[0081] Advantageously, the electrolyte contains SO4 in an amount of 500ppm or less by weight, preferably 200ppm or less, more preferably 100ppm or less, and in certain cases 50ppm or less or 20ppm or less 2- ions. SO4 2- ions may be substantially absent, or may be present in an amount of 0.1ppm, 1ppm, 2ppm, 5ppm or 10ppm or more by weight. For example, SO4 2- ions may be present in an amount of 0.1 to 500ppm, or 1 to 200ppm, or 2 to 100ppm, or 5 to 50ppm, or 10 to 20ppm by weight.

[0082] Advantageously, the electrolyte contains Na in an amount of 100ppm or less by weight, preferably 50ppm or less, more preferably 20ppm or less, and in certain cases 10ppm or less or 5ppm or less + ions. Na + ions may be substantially absent, or may be present in an amount of 0.1ppm or more by weight. For example, Na + ions may be present in an amount of 0.1 to 100ppm, or 0.1 to 50ppm, or 0.1 to 20ppm, or 0.1 to 10ppm, or 0.1 to 5ppm by weight.

[0083] Advantageously, the electrolyte is K in an amount of 100 ppm or less by weight, preferably 50 ppm or less, preferably 20 ppm or less, and in specified cases 10 ppm or less or 5 ppm or less. + Contains ions. K + Ions may be essentially absent, or they may be present in amounts of 0.1 ppm or more by weight. For example, K + Ions may be present in amounts of 0.1 to 100 ppm by weight, or 0.2 to 50 ppm, or 0.3 to 20 ppm, or 0.4 to 10 ppm, or 0.5 to 5 ppm.

[0084] Advantageously, the electrolyte contains alkali metals and alkaline earth metal ions (Li) in an amount of 100 ppm or less by weight, preferably 50 ppm or less, preferably 20 ppm or less, and in specified cases 10 ppm or less or 5 ppm or less. + Includes alkali metals and alkaline earth metal ions (Li + (Excluding ions) may be essentially absent or present in amounts of 0.1 ppm or more by weight. For example, alkali metal and alkaline earth metal ions (Li + (Ions excluded) may be present in total amounts of 0.1 to 100 ppm, or 0.2 to 50 ppm, or 0.3 to 20 ppm, or 0.4 to 10 ppm, or 0.5 to 5 ppm by weight.

[0085] The ion content in the electrolyte can be analyzed by ion chromatography and / or inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma atomic emission spectrometry (ICP-AES) and / or X-ray fluorescence analysis (XRF).

[0086] The electrolyte may contain a total water content of 3% by weight or less, preferably 2% by weight or less, or 1% or less, or 1000 ppm or less, or 500 ppm or less, or 200 ppm or less. The electrolyte may contain a total water content of 0.1 ppm or more by weight, preferably 1 ppm or more, or 5 ppm or more, or 10 ppm or more. The electrolyte may contain a total water content of 0.1 ppm to 3% by weight, preferably 1 ppm to 1000 ppm, or 5 ppm to 500 ppm, or 10 ppm to 200 ppm.

[0087] [Electrolyte preparation] Electrolytes can be prepared by mixing LiFSI salts with ionic liquids and other optional components (organic solvents, additional salts, additives).

[0088] During this mixing process, the ionic liquid can be added in an amount of 1% to 90% by weight, preferably 20% to 80% by weight, and more preferably 40% to 80% by weight, relative to the mixed components. In some embodiments, the ionic liquid can be added in an amount of 1% to 10%, or 10% to 20%, or 20% to 30%, or 30% to 40%, or 40% to 50%, or 50% to 60%, or 60% to 70%, or 70% to 80%, or 80% to 90% by weight (relative to the mixed components).

[0089] During this mixing step, the LiFSI salt can be blended at a concentration of 0.1 M to 6 M, preferably 0.2 M to 4 M, relative to the total of the ionic liquid and the organic solvent (if present). In some embodiments, the LiFSI salt can be blended at a concentration of 0.1 M to 0.2 M, or 0.2 M to 0.5 M, or 0.5 M to 1 M, or 1 M to 2 M, or 2 M to 3 M, or 3 M to 4 M, or 4 M to 5 M, or 5 M to 6 M, relative to the total of the ionic liquid and the organic solvent (if present).

[0090] During this mixing process, additional lithium salts may be added in an amount of 10% or less by weight, preferably 5% or less, relative to the mixed components. This amount may be particularly between 0.1% and 10%, or between 0.2% and 5%, or between 0.5% and 2% by weight.

[0091] During this mixing process, the additive may be incorporated in an amount of 10% or less by weight, preferably 5% or less, relative to the mixed components. This amount may be particularly between 0.1% and 10%, or between 0.2% and 5%, or between 0.5% and 2% by weight.

[0092] Ionic liquids can be prepared by the following process: - Selective prior synthesis of hydrogen bis(fluorosulfonyl)imides, i.e., HFSIs, compounds of the formula NH(SO2F)2; - Reaction of HFSI with a phosphonium cation precursor to obtain a reaction mixture containing a bis(fluorosulfonyl)imide anion; - Optional purification of reaction mixtures.

[0093] HFSI can synthesize chlorinated compounds of the formula NH(SO2R)(SO2R') by fluorination, where R and R' independently represent halogen (F or Cl) atoms, and at least one of them is a chlorine atom. Preferably, the chlorinated compound is hydrogen bis(chlorosulfonyl)imide.

[0094] Fluorination is carried out by contacting a chlorinated compound with a fluorinating agent, the fluorinating agent being selected from the group consisting of preferably HF (preferably anhydrous HF), KF, AsF3, BiF3, ZnF2, SnF2, PbF2, CuF2 and mixtures thereof, the fluorinating agent being more preferably HF, and even more preferably anhydrous HF. The term "anhydrous HF" is understood to mean HF containing less than 500 ppm of water, preferably less than 300 ppm of water, and preferably less than 200 ppm of water.

[0095] Fluorination is preferably carried out in at least one organic solvent OS1. The organic solvent OS1 preferably has a donor number between 1 and 70, and more favorably between 5 and 65. The donor number of the solvent is expressed by the value of -ΔH, where ΔH is the interaction enthalpy between the solvent and antimony pentachloride (as described in the Journal of Solution Chemistry, Vol. 13, No. 9, 1984). Examples of organic solvent OS1 include esters, nitriles, dinitriles, ethers, diethers, amines, phosphines, and mixtures thereof.

[0096] Preferably, the organic solvent OS1 is selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate, acetonitrile, propionitrile, isobutyronitrile, glutaronitrile, dioxane, tetrahydrofuran, triethylamine, tripropylamine, diethylisopropylamine, pyridine, trimethylphosphine, triethylphosphine, diethylisopropylphosphine, and mixtures thereof. In particular, the organic solvent OS1 is dioxane.

[0097] Fluorination can be carried out at a temperature between 0°C and the boiling point of the organic solvent OS1 (or a mixture of organic solvent OS1). Preferably, step b) is carried out at a temperature between 5°C and the boiling point of the organic solvent OS1 (or a mixture of organic solvent OS1), and more preferably between 20°C and the boiling point of the organic solvent OS1 (or a mixture of organic solvent OS1).

[0098] Preferably, fluorination with anhydrous hydrogen fluoride can be carried out at a pressure between 0 bar abs and 16 bar abs.

[0099] Fluorination is preferably carried out by dissolving the chlorinated compound in an organic solvent OS1 or a mixture of organic solvent OS1, and then reacting it with a fluorinating agent (preferably anhydrous HF).

[0100] The weight ratio of the chlorinated compound to the organic solvent OS1, or a mixture of organic solvent OS1, is preferably between 0.001 and 10, and more favorably between 0.005 and 5.

[0101] According to one embodiment, anhydrous HF is introduced into the reaction medium, preferably in gaseous form.

[0102] The molar ratio of the fluorinating agent, preferably anhydrous HF, to the chlorinated compound is preferably between 1 and 10, and more preferably between 1 and 5.

[0103] The reaction with a fluorinating agent, preferably anhydrous HF, can be carried out in a closed system or an open system, preferably an open system.

[0104] Fluorination reactions typically produce HCl, and most of this HCl can be removed from the reaction medium by stripping with a neutral gas (such as nitrogen, helium, or argon) (as well as excess HF if the fluorinating agent is HF).

[0105] However, residual HF and / or residual HCl may dissolve in the reaction medium. In the case of HCl, the amount is very small because at the operating pressure and temperature, HCl is mainly in gaseous form.

[0106] The product obtained after the fluorination reaction can be stored in an HF-resistant container.

[0107] The product obtained after the fluorination reaction may include HF (especially unreacted HF), chlorinated compounds, solvent OS1 (e.g., dioxane), and possibly HCl and / or possibly heavy compounds.

[0108] After the reaction, HFSI can be purified, in particular, by one or more distillation steps.

[0109] According to one embodiment, the following can be produced and recovered by distillation: - A first flow F1 at the top of the distillation column, preferably gaseous or liquid, containing HF, and optionally an organic solvent OS1 and / or HCl; - A second flow F2 at the bottom of the distillation column, preferably a liquid, containing HFSI and possibly heavy compounds. It becomes possible to generate and collect them.

[0110] If stream F2 contains heavy compounds, it is subjected to an additional distillation step in a second distillation column. - A flow F2-1 at the top of the distillation column, preferably a liquid, containing HFSI that does not contain heavy compounds; - The composition obtained in the flow F2-2 (flow F2-2 is step b), preferably at the bottom of the distillation column and containing heavy compounds and HFSI, contains less than 10% by weight, preferably less than 7% by weight, and preferably less than 5% by weight of HFSI, and the flow F2-2 is preferably liquid. It becomes possible to generate and collect them.

[0111] The term "heavy compounds" is understood to mean organic compounds with boiling points higher than HFSI. These can be produced by cleavage reactions of chlorinated compounds that produce compounds such as FSO2NH2, and / or decomposition reactions of solvents that produce oligomers.

[0112] According to one embodiment, the distillation step, - A first flow F'1 at the top of the distillation column, preferably gaseous or liquid, containing HF, and possibly an organic solvent OS1 and / or possibly HCl; - A second flow F'2 containing HFSI, preferably recovered by side-flow extraction (the flow F'2 is preferably liquid); - The composition obtained in the third flow F'3 (flow F'3 is step b) at the bottom of the distillation column, which contains heavy compounds and HFSI, contains less than 10% by weight, preferably less than 7% by weight, and preferably less than 5% by weight of HFSI, and flow F'3 is preferably liquid. It becomes possible to generate and collect them.

[0113] To implement side-flow extraction, the distillation column may include at least one tray.

[0114] The distillation step can be carried out at a pressure ranging from 0 to 5 bar abs, preferably 0 to 3 bar abs, more preferably 0 to 2 bar abs, and advantageously 0 to 1 bar abs.

[0115] The distillation stage can be carried out in any conventional apparatus, which may be a distillation apparatus comprising a distillation column, a boiler, and a condenser. The distillation column may be equipped with at least one type of packing material, e.g., random packing and / or structured packing, and / or trays, e.g., perforated trays, fixed valve trays, movable valve trays, bubble cap trays, or a combination thereof.

[0116] After purification is complete, HFSI can be recovered in high purity. Using high-purity HFSI offers the advantage of avoiding complex subsequent purification steps, making it possible to prepare high-purity ionic liquids.

[0117] The recovered product (and / or used in reaction with the phosphonium cation precursor) thus preferably contains at least 95% by weight of HFSI, more preferably 98% by weight, at least 99% by weight, at least 99.5% by weight, and indeed even more than 99.8% by weight of HFSI.

[0118] The recovered product (and / or the product used in the reaction with the phosphonium cation precursor) preferably has a sulfamic acid content of 5000 ppm by weight or less, more preferably 4000 ppm by weight or less, 3000 ppm by weight or less, 2500 ppm by weight or less, and even actually 2000 ppm by weight or less. In certain cases, sulfamic acid may be substantially absent, or may be present in a content of at least 1 ppm by weight. The sulfamic acid content may particularly be from 1 to 5000 ppm, from 10 to 4000 ppm, from 100 to 3000 ppm, or from 500 to 2500 ppm by weight. It may, for example, be from 1 to 10 ppm, from 10 to 50 ppm, from 50 to 100 ppm, from 100 to 200 ppm, from 200 to 500 ppm, from 500 to 1000 ppm, from 1000 to 2000 ppm, from 2000 to 3000 ppm, from 3000 to 4000 ppm, or from 4000 to 5000 ppm by weight. The sulfamic acid content can be quantified by ion chromatography (NH2SO3 - as expressed).

[0119] For ion chromatography measurement, a Thermo ICS-5000 instrument can particularly be used. The instrument is provided with two analysis channels, one of which is dedicated to anion analysis, - Supply of ultrapure water (18.2 MΩ) by a dual piston pump; - Automatic eluent generator (EGC); - Valve with injection loop (volume = 25 microliters); - Guard column (AG19, T = 35°C) and separation column (AS19, T = 20°C); - Suppressor (AERS 62mA); - Conductivity meter for peak detection comprising the above components.

[0120] The eluent used may be a KOH solution with a concentration of 25 mmol / l, and may have a flow rate of 1 ml / min.

[0121] The term "phosphonium cation precursor" is understood to mean any compound that can react with HFSI to produce an FSI anion in combination with a phosphonium cation.

[0122] In particular, phosphonium cation precursors are phosphonium cation halides, i.e., compounds AX (where A represents a halogen atom and X). + (where A represents a phosphonium cation). Preferably, the precursor is a chloride or bromide (where A is Cl or Br).

[0123] In this case, the reaction with HFSI produces an ionic liquid consisting of an FSI anion and a phosphonium cation, as well as a byproduct of formula HA (preferably HCl or HBr).

[0124] The reaction is preferably carried out in the absence (or essentially absence) of organic solvents, and optionally in the presence of water. The weight ratio of water to the phosphonium cation precursor can be, for example, 1:2 to 5:1, preferably 1:1 to 4:1, and more preferably 3:2 to 3:1.

[0125] The molar ratio of HFSI added in the presence of a phosphonium cation precursor is preferably 0.9 to 1.1, more preferably 1 to 1.05, and more preferably 1 to 1.01.

[0126] The temperature of the reaction medium is preferably 10°C to 100°C, more preferably 20°C to 30°C.

[0127] In some embodiments, a phosphonium cation precursor is poured onto an HFSI in a molten state and maintained at a desired temperature.

[0128] In other embodiments, the HFSI is added in a molten state to a phosphonium cation precursor that has been liquefied by adding water. The weight ratio of water to the phosphonium cation precursor can be, for example, 0.02 to 6, preferably 0.5 to 5, preferably 1 to 4, and more preferably 1.5 to 3.

[0129] Water may be present in the reaction medium in an amount of 1% to 90%, preferably 2% to 80%, more preferably 5% to 70%, or 10% to 60% by weight relative to the total weight of the phosphonium cation precursor and HFSI.

[0130] The progress of the reaction can be monitored by the release of by-products, particularly the by-product of formula HA.

[0131] This allows the ionic liquid to be obtained in high yield, preferably 70% or higher.

[0132] After the reaction, the reaction medium containing the ionic liquid can be purified under atmospheric pressure or preferably under vacuum by, for example, washing, sedimentation (or any other aqueous phase separation), and drying. A decolorization step can also be provided, for example, by contact with activated carbon. However, in a preferred embodiment, the decolorization step is omitted.

[0133] If decolorization is performed, it can be carried out by contacting the activated carbon with an ionic liquid at a weight ratio of 0.05 to 0.5, preferably 0.1 to 0.5, of activated carbon to ionic liquid. The activated carbon is measured, for example, by the BET method by nitrogen adsorption, at 300 m 2 It exceeds / g, and indeed even more so at 1000m 2 It may have a specific surface area greater than / g. The duration of the contact operation may be particularly 1 to 72 hours, preferably 5 to 48 hours. The temperature during the contact operation may range from 10°C to the boiling point of any solvent that may be present with the ionic liquid, or, if no solvent is present, may be higher than the melting point of the ionic liquid. After the decolorization step is complete, the activated carbon can be separated from the decolorized ionic liquid by, for example, filtration using a polytetrafluoroethylene or poly(vinylidene fluoride) membrane, a cellulose membrane, or a filtration medium (silica, alumina, diatomaceous earth).

[0134] Washing can be carried out in an aqueous system, which involves contacting an ionic liquid with an aqueous solution (water containing one or more dissolved substances) or preferably demineralized water.

[0135] The ionic liquid to be washed with an aqueous system can be dissolved in a water-insoluble polar organic solvent beforehand. Preferably, the water-insoluble polar organic solvent is selected from the group consisting of butyl acetate, ethyl acetate, tert-butyl acetate, butyronitrile, isobutyronitrile, glutalonitrile, diethyl ether, cyclopentyl methyl ether, tetrahydrofuran, methyl isobutyl ketone, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, ethylene carbonate, and propylene carbonate.

[0136] However, preferably, no organic solvent is used at this stage.

[0137] Water-based washing makes it possible to reduce and remove impurities present in ionic liquids, such as chloride ions, fluoride ions, sulfate ions, and sulfamate ions.

[0138] During each aqueous washing system, the weight ratio of the aqueous washing solution, preferably demineralized water, to the ionic liquid is preferably 0.01 to 5, for example, 0.01 to 0.05, or 0.05 to 0.1, or 0.1 to 0.5, or 0.5 to 1, or 1 to 2, or 2 to 5. A ratio of 1 to 0.5 is preferred.

[0139] The time required for contact between the ionic liquid and the aqueous cleaning solution can be varied from 1 second to 24 hours. Specifically, it can be 1 second to 1 minute, 1 minute to 10 minutes, 10 minutes to 30 minutes, 30 minutes to 1 hour, 1 hour to 2 hours, 2 hours to 3 hours, 3 hours to 4 hours, 4 hours to 5 hours, 5 hours to 6 hours, 6 hours to 12 hours, or 12 hours to 24 hours. For the shortest contact time, a static mixer can also be used.

[0140] Washing may involve sedimentation to separate the aqueous phase from the organic phase. The organic phase is rich in ionic liquids and low in impurities (e.g., low in chloride, fluoride, sulfuric acid, and sulfamate ions). That is, in the organic phase, the molar concentration ratio of ionic liquids to impurities (especially chloride, fluoride, sulfuric acid, and sulfamate ions) is higher than the molar concentration ratio of the original ionic liquids. The aqueous phase is rich in impurities (e.g., rich in chloride, fluoride, sulfuric acid, and sulfamate ions). That is, in the aqueous phase, the molar concentration ratio of ionic liquids to impurities (especially chloride, fluoride, sulfuric acid, and sulfamate ions) is lower than the molar concentration ratio of the original ionic liquids. The aqueous phase can then be removed.

[0141] Several aqueous washes can be performed, particularly 2 to 11 aqueous washes (for example, 2, 3, 4, 5, or 10 washes). When performing several washes, each wash can be performed independently as described above. Preferably, the next wash is performed on the organic phase obtained by sedimentation separation after the completion of the previous wash.

[0142] After this or these steps are completed, the solvent of the organic phase, if present, can be removed, preferably under reduced pressure, for example, by evaporation of the solvent. A purified ionic liquid is thus obtained.

[0143] The obtained product can be characterized by analysis of its water content by nuclear magnetic resonance spectroscopy, Karl Fischer assay, and analysis of its anion and cation content by ion chromatography.

[0144] [Electrochemical cells and batteries] The electrolytes described above can be introduced into an electrochemical cell. The electrochemical cell comprises a negative electrode (or anode) and a positive electrode (or cathode). The electrochemical cell may also comprise a separator impregnated with the electrolyte.

[0145] The term "negative electrode" is understood to refer to the electrode that acts as the anode when the cell is supplying current (i.e., in the discharge phase) and as the cathode when the cell is charging.

[0146] The negative electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.

[0147] The term "positive electrode" is understood to refer to the electrode that acts as the cathode when the cell is supplying current (i.e., in the discharge phase) and as the anode when the cell is charging.

[0148] The positive electrode typically comprises an electrochemically active material, optionally an electronically conductive material, and optionally a binder.

[0149] The term "electrochemically active material" is understood to mean a material that can reversibly insert ions.

[0150] The term "electronically conductive material" is understood to mean a material that can conduct electrons.

[0151] The negative electrode of an electrochemical cell is made of electrochemically active materials, such as graphite, lithium, lithium alloys, and Li4Ti5O. 12 It may contain lithium titanate of a certain type, or titanium oxide (TiO2), silicon or lithium silicon alloy, tin oxide, lithium intermetallic compounds, or a mixture thereof.

[0152] When the negative electrode contains lithium, the lithium may be in the form of a thin film of lithium metal or a lithium-containing alloy. For example, usable lithium-based alloys include lithium aluminum alloy, lithium silica alloy, lithium tin alloy, Li-Zn, Li3Bi, Li3Cd, and Li3SB. An example of a negative electrode may include an activated lithium thin film prepared by rolling a strip of lithium between rollers.

[0153] The negative electrode may simply consist of a current collector, for example made of copper; in this case, lithium metal, which constitutes the active material of the electrode, is deposited on the current collector during charging.

[0154] Preferably, the negative electrode comprises silicon as an electrochemically active material, optionally mixed with graphite. The weight proportion of silicon in the electrochemically active material may be 10% or more, preferably 20% or more. This proportion may in particular be from 10% to 100%, or from 20% to 99%, or from 30% to 98%, or from 50% to 95%. The electrochemically active material may be micro- or nanostructures in the form of, for example, nanoparticles, porous or non-porous fine particles, nanowires, or nanotubes. The surface of the silicon particles has Si-C bonds or SiO x (0<x≦2) bonds may be included.

[0155] The positive electrode comprises an oxide-type electrochemically active material. The positive electrode is preferably lithium iron phosphate (Li where 0<x<1 x FePO4), or a lithium / nickel / manganese / cobalt composite oxide having a high nickel content (LiNi where x+y+z=1 x Mn y Co z O2, abbreviated as NMC, where x>y and x>z), or a lithium / nickel / cobalt / aluminum composite oxide having a high nickel content (LiNi where x'+y'+z'=1 x’ Co y’ Al z’ , abbreviated as NCA, where x'>y' and x'>z').

[0156] Specific examples of these oxides include NMC532 (LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC622 (LiNi 0.6 Mn 0.2 Co 0.2 O2) and NMC811 (LiNi 0.8 Mn 0.1 Co 0.1 O2).

[0157] Mixtures of these oxides can also be used. The oxide materials mentioned above can be, as needed, for example, manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium / manganese composite oxide (e.g., Li x Mn2O4 or Li x MnO2), lithium / nickel oxide composite (e.g., Li x NiO2), lithium / cobalt composite oxide (e.g., Li x CoO2), lithium / nickel / cobalt composite oxide (e.g., LiNi 1-y Co y O2), lithium and transition metal composite oxides, spinel structure lithium / manganese / nickel composite oxides (e.g., Li x Mn 2-y Ni y O4) can be combined with other oxides such as vanadium oxide, NMC and NCA oxides that do not have a high nickel content, and mixtures thereof.

[0158] Preferably, the high nickel-content NMC or NCA oxide constitutes at least 50% by weight, preferably at least 75% by weight, more preferably at least 90% by weight, and more preferably essentially all, of the oxide material present in the positive electrode as an electrochemically active material.

[0159] Alternatively, or in addition, the positive electrode may contain sulfur, Li2S, O2, and / or LiO2 as electrochemically active materials.

[0160] The materials of each electrode may also include, in addition to electrochemically active materials, electronically conductive materials such as carbon black, Ketjen® carbon, Schawinigan carbon, graphite, graphene, carbon nanotubes, carbon fibers (e.g., vapor-grown carbon fibers or VGCF), carbon sources such as non-powdered carbon obtained by carbonization of organic precursors, or combinations of two or more of these. The cathode material may also contain other additives such as lithium salts or ceramic or glassy inorganic particles, or other suitable active materials (e.g., sulfur).

[0161] The material of each electrode may also contain a binder. Non-limiting examples of binders include linear, branched, and / or crosslinked polyether polymer binders (e.g., polymers based on poly(ethylene oxide) (PEO) or poly(propylene oxide) (PPO), or mixtures thereof (or EO / PO copolymers) containing optionally crosslinkable units), water-soluble binders (e.g., SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), HNBR (hydrogenated NBR), CHR (epichlorohydrin rubber), ACM (acrylate rubber)), or fluoropolymer-type binders (e.g., PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene)) and combinations thereof. Certain binders, such as water-soluble ones, may also contain additives such as CMC (carboxymethylcellulose) or alginates.

[0162] Preferably, the negative electrode contains a binder selected from polyacrylic acid, carboxymethylcellulose, alginate, and PVDF.

[0163] The separator may be a porous polymer film. In non-limiting examples, the separator may consist of a porous film of polyolefin such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, or ethylene / methacrylate copolymer, or a multilayer structure of the above polymers. Alternatively, the separator may consist of glass fibers.

[0164] The present invention also relates to a battery comprising at least one, preferably several, of the above-described electrochemical cells. The electrochemical cells can be assembled in series and / or parallel within the battery.

[0165] The battery can be incorporated into portable electronic devices, such as mobile phones or laptop computers, electric vehicles, or renewable energy storage devices, such as solar or wind power generation.

Claims

1. - It is an ionic liquid, • Bis(fluorosulfonyl)imide anion, and ・ formula (PR １ R ２ R ３ R ４ ) ＋ (wherein each R １ , R ２ , R ３ and R ４ group independently represents a saturated or unsaturated linear or branched alkyl group having 1 to 14 carbon atoms, an alkyl-aryl group having 7 to 14 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R １ , R ２ , R ３ and R ４ group may optionally contain one or more heteroatoms) at least one phosphonium cation Ionic liquids containing; and - Lithium bis(fluorosulfonyl)imide salt An electrolyte containing a sulfamate ion with a content of 0.1 to 3000 ppm by weight.

2. Phosphonium cations include tetraethylphosphonium, tetrabutylphosphonium, trimethyl(propyl)phosphonium, trimethyl(hexyl)phosphonium, trimethyl(2-methylpropyl)phosphonium, triethyl(methyl)phosphonium, triethyl(butyl)phosphonium, triethyl(pentyl)phosphonium, triethyl(hexyl)phosphonium, tributyl(methyl)phosphonium, tri(2-methylpropyl)(methyl)phosphonium, trihexyl(dodecyl)phosphonium, trihexyl(tetradecyl)phosphonium, dimethyldipropylphosphonium, diethyl(methyl)(2-methylpropyl)phosphonium, and The electrolyte according to claim 1, selected from ributyl(6-hepten-1-yl)phosphonium, tetraphenylphosphonium, triphenyl(methyl)phosphonium, trimethyl(methoxymethyl)phosphonium, triethyl(methoxymethyl)phosphonium, triethyl(2-methoxyethyl)phosphonium, triethyl[(methylthio)methyl]phosphonium, triethyl[2-(methylthio)ethyl]phosphonium, triethyl[2-(ethylthio)ethyl]phosphonium, tributyl[(methylthio)methyl]phosphonium, tributyl[2-(methylthio)ethyl]phosphonium, and tributyl[2-(ethylthio)ethyl]phosphonium.

3. The electrolyte according to claim 1 or 2, wherein the sulfamate ion content is 1 to 1000 ppm by weight, preferably 10 to 300 ppm.

4. The electrolyte according to any one of claims 1 to 3, wherein the ionic liquid is present in a weight content of 1% to 90%, preferably 20% to 80%.

5. The electrolyte according to any one of claims 1 to 4, comprising at least one organic solvent.

6. The electrolyte according to any one of claims 1 to 5, wherein the lithium bis(fluorosulfonyl)imide salt is present at a concentration of 0.1 M to 6 M, preferably 0.2 M to 4 M, relative to the total amount of the ionic liquid and optionally present organic solvent.

7. A method for preparing an electrolyte according to any one of claims 1 to 6, comprising the step of mixing a lithium bis(fluorosulfonyl)imide salt with an ionic liquid.

8. Ionic liquids, - Providing bis(fluorosulfonyl)imide compounds; and - Reaction of bis(fluorosulfonyl)imide with phosphonium cation precursor The method according to claim 7, which is prepared by...

9. The method according to claim 8, wherein the bis(fluorosulfonyl)imide has a sulfamic acid content of 1 to 5000 ppm by weight, preferably 500 to 2500 ppm.

10. The method according to claim 8 or 9, wherein the phosphonium cation precursor is a halogenated phosphonium cation, preferably a chloride or bromide of a phosphonium cation.

11. The reaction was, - Without using organic solvents, and optionally in the presence of water; and / or - In a molar ratio of bis(fluorosulfonyl)imide / phosphonium cation precursor of 0.9 to 1.1, preferably 1 to 1.05, more preferably 1 to 1.01; and / or - At temperatures between 10°C and 100°C, preferably between 20°C and 30°C The method according to any one of claims 8 to 10, which is implemented.

12. - A step in which the reaction mixture is purified after the reaction, preferably by washing, sedimentation, and / or drying. The method according to any one of claims 8 to 11, including

13. An electrochemical cell comprising a negative electrode, a positive electrode, and an electrolyte, wherein the electrolyte is as described in any one of claims 1 to 6.

14. The electrochemical cell according to claim 13, wherein the negative electrode contains an electrochemically active material including silicon in a weight content of preferably 10% or more, more preferably 20% or more.

15. A battery comprising at least one electrochemical cell as described in claim 13 or 14.

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