Liquid electrolyte comprising sulfonamides and at least two lithium salts and use thereof

Abstract

The present invention relates to a liquid electrolyte comprising: i. At least one sulfonamide of general formula I, ii. A combination of at least two lithium salts; and iii. At least one co-solvent and / or one filler; and wherein the liquid electrolyte does not comprise an organic carbonate. The invention also relates to an electrochemical cell and to the use thereof, as well as to a method for producing a liquid electrolyte and an electrochemical cell.

Description

Technical Field

[0001] This invention relates to the field of liquid electrolytes used in electrochemical single-cell batteries or batteries. This invention can find wide applications in energy storage and electronic devices. Background Technology

[0002] Lithium metal batteries (LMBs) undoubtedly represent an attractive technology for energy storage applications due to their high energy density. Commercial batteries primarily use liquid electrolytes (LEs) as ion transport media because of their high ionic conductivity and excellent wettability to electrodes and separators. On the other hand, solid electrolytes (such as those made of polymers, ceramics, or mixtures thereof) are characterized by lower conductivity than existing liquid electrolytes.

[0003] Typical liquid electrolytes are organic carbonates and ethers, such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), and 1,2-dimethoxyethane (DME). However, liquid carbonate electrolytes may involve high flammability, low thermal stability, and suboptimal electrode-electrolyte interface resistance. These issues are major obstacles to the practical use of liquid electrolytes in liquid metallurgical batteries (LMBs).

[0004] Several sulfonamides have been used as components of liquid electrolytes; however, other organic carbonates are usually required to achieve stable electrochemical cycling.

[0005] For example, document EP3050872Al relates to a solvent system containing a component according to general formula R. 1 -SO2-NR2R3 fluorinated sulfonamide and electrolyte salt electrolyte solution, however, the literature teaches that flammable carbonate solvents are essential for solving the corresponding technical problems (e.g., aluminum current collector corrosion) while maintaining high electrolyte conductivity.

[0006] US9065146B2 describes a non-aqueous electrolyte comprising a non-aqueous organic solvent and a lithium salt dissolved therein, wherein the non-aqueous organic solvent comprises at least one compound selected from acid anhydrides and carbonates having unsaturated bonds, and at least one compound selected from sulfonic acid compounds and fluorinated aromatic compounds having nine or fewer carbon atoms.

[0007] WO2022216593A1 discloses an electrolyte and electrochemical cell comprising asymmetric sulfonamide, lithium salt and carbonate.

[0008] US8802301B2 relates to an ionic liquid composition as an electrolyte for lithium-ion batteries, comprising alkylsulfonamides or arylsulfonamides and lithium fluoroalkylsulfonamides or lithium fluoroarylsulfonamides at a specific sulfonamide / lithium salt ratio and with a Tg of less than -50°C.

[0009] WO2022053881A1 discloses an electrolyte composition comprising one or more sulfonyl-based solvents for use in electrochemical devices such as secondary batteries. The electrolyte may comprise one or more salts, such as one or more alkali metal salts, dissolved in the sulfonyl-based solvent system.

[0010] US2024 / 322244 describes a liquid electrolyte comprising a lithium salt composition, a solvent composition, and a diluent composition, wherein the diluent composition comprises a fluorinated or non-fluorinated alkane.

[0011] Xue Weijiang et al. (Energy & Environmental Science, 2020, 13(1), 212-220) described a liquid electrolyte containing a combination of dimethylaminosulfonyl fluoride and two lithium salts (i.e., LiFSI and LiPF6) without any co-solvent.

[0012] Despite progress in this field, electrolyte systems exhibiting improved safety, stability to Li metal anodes, improved interfacial resistance, and / or resulting in high conductivity remain to be discovered. Therefore, there is a need in the art to develop new electrolyte systems, particularly liquid electrolytes, that overcome the safety and Li metal stability issues of existing liquid electrolytes while simultaneously providing feasible electrochemical performance for a wide range of applications. Summary of the Invention

[0013] This invention relates to a liquid electrolyte comprising sulfonamide, at least two lithium salts, and a co-solvent. The inventors have discovered that such electrolyte compositions enable the development of electrochemical cells exhibiting advantageous properties, such as high Li metal stability, improved safety, and improved interfacial resistance, without compromising electrolyte conductivity. Furthermore, the liquid electrolyte of this invention provides an electrochemical cell that exhibits superior capacity retention and a coulombic efficiency exceeding 99% compared to cells with other liquid electrolytes that do not contain a co-solvent or contain only one lithium salt.

[0014] Furthermore, the electrolyte composition is characterized by being free of organic carbonates, as the presence of such carbonates has been shown to significantly affect the cyclability of batteries containing liquid electrolytes.

[0015] Therefore, a first aspect of the present invention relates to a liquid electrolyte comprising:

[0016] i. At least one sulfonamide having the general formula I,

[0017]

[0018] in

[0019] R1 and R2 are each independently selected from linear or branched C1-C atoms that can be substituted by one or more fluorine atoms. 12 Alkyl groups, linear or branched C2-C atoms that may be substituted with one or more fluorine atoms. 12 Alkenyl groups, C6-C atoms that can be substituted with one or more fluorine atoms 12 Aryl groups, and CH2CH2O-(CH2CH2O) n -R3, where R3 is methyl or ethyl, and n is an integer from 0 to 20; or R1 and R2 may combine with each other to form a nitrogen-containing aliphatic ring;

[0020] ii. A combination of at least two lithium salts selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF2H)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(SO2CHF2)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3; and

[0021] iii. At least,

[0022] a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Propyl phosphate (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or

[0023] b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers;

[0024] Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

[0025] The second aspect of the present invention relates to an electrochemical single-cell battery or battery comprising the liquid electrolyte and positive electrode of the first aspect of the present invention.

[0026] The third aspect of the invention relates to the use of the electrochemical single cell or battery of the second aspect in the following: electric motors; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; light electric vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems.

[0027] A fourth aspect of the present invention relates to a method for preparing the liquid electrolyte of the first aspect, comprising the following steps:

[0028] (i) Provide a combination of at least two lithium salts;

[0029] (ii) Mix at least one sulfonamide of formula I with the salt of step (i);

[0030] (iii) Add at least:

[0031] a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Propyl phosphate (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) nF, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or

[0032] b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers; and

[0033] (iv) The mixture obtained by stirring.

[0034] The fifth aspect of the present invention relates to a method for preparing an electrochemical single-cell battery or battery of the second aspect, comprising the following steps:

[0035] (i) Providing a positive electrode for an electrochemical single cell or battery;

[0036] (ii) Provide a negative electrode for an electrochemical single cell or battery;

[0037] (iii) Providing a liquid electrolyte as defined in the first aspect of the invention or in any preferred or particular embodiment thereof; and

[0038] (iv) The surfaces of the positive electrode provided in step (i) and the negative electrode provided in step (ii) are coated with the electrolyte provided in step (iii) in such a manner that the electrolyte is arranged between the positive and negative electrodes so that lithium cations can flow from the positive electrode to the negative electrode, said surfaces optionally being covered with porous separators before being coated with the electrolyte. Attached Figure Description

[0039] Figure 1 The capacity retention of Li°||LFP batteries containing the following electrolytes at 25 °C with respect to cycle number is shown: a) a mixture of 1.0 M LiFSI lithium salts in FSA11 (E1); b) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / triethylene glycol dimethyl ether at a 90 / 10 vol% solvent ratio (E2); c) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / EC at a 90 / 10 vol% solvent ratio (E3); and d) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / FEC at a 90 / 10 vol% solvent ratio (E4). Detailed Implementation

[0040] Unless otherwise stated, all terms used herein shall be understood in their ordinary meaning as known in the art. Unless otherwise expressly stated, more specific definitions of certain terms used herein are set forth below and are intended to be applied uniformly throughout the specification and claims.

[0041] Throughout the specification and claims, the word "comprising" and variations thereof are not intended to exclude other technical features, additives, components, or steps. Furthermore, the word "comprising" covers both "consisting of" and "substantially consisting of". Further objects, advantages, and features of the invention will become apparent to those skilled in the art after studying the specification, or may be learned through practice of the invention.

[0042] Throughout the specification and claims, the terms "blend" and "mixture" will be used interchangeably.

[0043] For the purposes of this invention, any range given includes both the lower and upper endpoints of the range. When a range or value (e.g., temperature, time, molar ratio, volume ratio, etc.) is defined by the term "about", it should be considered approximate (i.e., with a variation of 5% around the indicated point).

[0044] As mentioned above, a first aspect of the present invention relates to a liquid electrolyte comprising:

[0045] i. At least one sulfonamide having the general formula I,

[0046]

[0047] in,

[0048] R1 and R2 are each independently selected from linear or branched C1-C atoms that can be substituted by one or more fluorine atoms. 12 Alkyl groups, linear or branched C2-C atoms that may be substituted with one or more fluorine atoms. 12 Alkenyl groups, C6-C atoms that can be substituted with one or more fluorine atoms 12 Aryl groups, and CH2CH2O-(CH2CH2O) n -R3, where R3 is methyl or ethyl, and n is an integer from 0 to 20; or R1 and R2 may combine with each other to form a nitrogen-containing aliphatic ring;

[0049] ii. A combination of at least two lithium salts selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF2H)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(SO2CHF2)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3; and

[0050] iii. At least,

[0051] a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Propyl phosphate (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or

[0052] b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers;

[0053] Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

[0054] The following will provide an embodiment of the first aspect of the present invention.

[0055] sulfonamide

[0056] The liquid electrolyte of the present invention comprises at least one sulfonamide of Formula I as shown above. In the context of the present invention, the term "sulfonamide" refers to an organic compound containing a core functional group >NS(=O)2-, wherein the N atom is attached to organic moieties R1 and R2, and the S atom is further attached to a fluorine (F) atom. In one particular embodiment, the liquid electrolyte of the present invention comprises one sulfonamide of Formula I; in another particular embodiment, it comprises two or more sulfonamides of Formula I; and in yet another embodiment, it comprises three or more sulfonamides of Formula I. In a preferred embodiment, the liquid electrolyte of the present invention comprises only one sulfonamide of Formula I.

[0057] In one embodiment, groups R1 and R2 are the same. In another embodiment, groups R1 and R2 are different.

[0058] Typically, groups R1 and R2 are each independently selected from linear or branched C1-C groups that can be substituted with one or more fluorine atoms. 12 Alkyl groups, linear or branched C2-C atoms that may be substituted with one or more fluorine atoms. 12 Alkenyl groups, C6-C atoms that can be substituted with one or more fluorine atoms 12 Aryl groups, and CH2CH2O-(CH2CH2O) n -R3, where R3 is methyl or ethyl, and n is an integer from 0 to 20; or R1 and R2 may combine with each other to form a nitrogen-containing aliphatic ring.

[0059] As used in this article, “C1-C” 12 "Alkyl" refers to a branched or linear aliphatic carbon chain consisting of 1 to 12 carbon atoms. C1-C 12Illustrative examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, etc. In preferred embodiments, the aliphatic chain may contain fewer carbon atoms, such as 6 carbon atoms (“C1-C6 alkyl”) or 3 carbon atoms (“C1-C3 alkyl”). Methyl is the most preferred alkyl group. The alkyl chain may be partially or fully fluorinated (“perfluorinated”), meaning that at least one, but not all, hydrogen atoms in any CH bond are replaced by fluorine atoms, or that all hydrogen atoms in any CH bond are replaced by fluorine atoms.

[0060] As used in this article, “C2-C” 12 "Alkenyl" refers to a linear or branched aliphatic group having 2 to 12 carbon atoms and at least one C=C double bond. Such alkenyl groups include vinyl (-CH=CH2), n-2-propenyl (allyl, -CH2CH=CH2), etc.

[0061] As used in this article, "C6-C" 12 "Aryl" refers to an aromatic hydrocarbon ring containing 6 to 12 carbon atoms, and also as two fused rings, optionally substituted with alkyl groups as defined above, such as phenyl, α-naphthyl, β-naphthyl, m-methylphenyl, p-trifluoromethylphenyl, etc.

[0062] More specifically, R1 and R2 are each independently selected from linear or branched C1-C atoms that can be substituted by one or more fluorine atoms. 12 Alkyl groups, linear or branched C2-C atoms that may be substituted with one or more fluorine atoms. 12 Alkenyl groups, and CH2CH2O-(CH2CH2O) n -R3, where R3 is H or methyl, and n is an integer from 0 to 10; or R1 and R2 may combine with each other to form a 3- to 7-membered nitrogen-containing aliphatic ring.

[0063] Preferably, R1 and R2 are each independently selected from linear or branched C1-C6 alkyl groups that can be substituted with one or more fluorine atoms, linear or branched C2-C6 alkenyl groups that can be substituted with one or more fluorine atoms, and CH2CH2O-(CH2CH2O). n -R3, where R3 is H or methyl, and n is an integer from 0 to 10; or R1 and R2 may combine with each other to form a 3- to 7-membered nitrogen-containing aliphatic ring.

[0064] More preferably, R1 and R2 are each independently selected from linear or branched C1-C6 alkyl, linear or branched C2-C6 alkenyl, and CH2CH2O-(CH2CH2O). n -R3, where R3 is a methyl group and n is an integer from 0 to 5; or R1 and R2 can combine with each other to form a 3- to 7-membered nitrogen-containing aliphatic ring.

[0065] Even more preferably, R1 and R2 are each independently selected from linear C1-C6 alkyl, C2-C6 alkenyl and -CH2CH2OCH2CH2O-CH3 groups; or R1 and R2 can be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring.

[0066] Even more preferably, R1 and R2 are each independently selected from linear C1-C3 alkyl, C2-C3 alkenyl, and -CH2CH2O-CH3. More preferably, R1 and R2 are each independently selected from linear C1-C3 alkyl.

[0067] In the most preferred embodiment, R1=R2=CH3.

[0068] The range of at least one sulfonamide can be from 5% to 95% of the weight of the liquid electrolyte, preferably from 10% to 90% of the weight of the electrolyte, more preferably from 30% to 90% of the weight of the electrolyte; even more preferably from 50% to 90% of the weight of the electrolyte; and most preferably from 70% to 90% of the weight of the electrolyte.

[0069] In one particular embodiment, the electrolyte of the first aspect of the invention does not contain a polymer selected from: sulfonamide-containing polymers, polyoxyethylene, polyalkylene imides, polyalkylene sulfides, poly(meth)acrylates, polyphosphazenes, polysiloxanes, polyvinyl alcohol (PVA), polyvinylamine (PVAm), polyvinyl acetate (PVAc), polyhalogenated vinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), poly(vinylpyrrolidone) (PVP), poly(2-vinylpyridine), poly(ε-caprolactone) (PCL), polymaleimide and its alternating polymers with olefins, polyaniline (PANI), chitosan (CS), or any blends or copolymers or crosslinked polymers thereof.

[0070] lithium salts

[0071] The liquid electrolyte of the present invention comprises a combination of at least two lithium salts, preferably comprising at least the following lithium salt LiFSI.

[0072]

[0073] In this invention, the liquid electrolyte comprises a combination of at least two lithium salts selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF2H)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(SO2CHF2)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3.

[0074] In one embodiment, the combination of at least two lithium salts is selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3.

[0075] In another embodiment, the combination of at least two lithium salts is selected from LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, LiCF3SO3, and LiNO3.

[0076] In a preferred embodiment, the combination of at least two lithium salts is selected from LiN(SO2F)2, LiN(SO2CF3)(SO2CF2H), LiB(C2O4)2, LiBF2(C2O4), LiN(SO2CF3)2 and LiN(SO2CF3)(SO2F); more preferably selected from LiN(SO2F)2, LiN(SO2CF3)(SO2CF2H), LiB(C2O4)2, LiBF2(C2O4), LiN(SO2CF3)2 and LiN(SO2CF3)(SO2F); and even more preferably selected from LiN(SO2F)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)2 and LiBF2(C2O4).

[0077] In a preferred embodiment, the combination of at least two lithium salts is LiN(SO2F)2 and LiBF2(C2O4), also referred to as LiFSI and LiDFOB, respectively.

[0078] In one particular embodiment, the liquid electrolyte contains at least two lithium salts ranging from 5% to 45% by weight, preferably from 5% to 40% by weight, more preferably from 5% to 25% by weight, even more preferably from 8% to 18% by weight, most preferably from 10% to 15% by weight, and even most preferably about 12% by weight, relative to the total weight of the electrolyte.

[0079] Organic carbonates

[0080] The electrolyte of the present invention is further characterized in that it does not contain organic carbonates. For the purposes of this invention, any carbonate containing an organic, cyclic, or linear chain having at least C and H atoms (O=C(-O)) is considered an organic carbonate. - Both )2 must be considered organic carbonates. Organic carbonates are preferably liquids at room temperature. As practical examples, although the list is non-limiting, the definition of organic carbonates includes cyclic alkylene carbonates (ethylene carbonate, propylene carbonate, butylene carbonate, etc.) and di(alkyl) carbonates (e.g., dialkyl carbonates, diaryl carbonates, alkylaryl carbonates) or mixtures thereof.

[0081] Substituted derivatives of the aforementioned organic carbonates are also excluded from the liquid electrolytes of this invention. One or more substituents may be present on the alkylene, alkyl, or aryl moiety. Non-limiting examples of substituents include halogens, alkoxy groups, hydroxyl groups, nitrogen substituents, phosphorus substituents, sulfur substituents, and similar moieties.

[0082] As can be seen from the following example, the presence of carbonates in a liquid electrolyte composition adversely affects the cyclability of the battery into which it is incorporated, with a significant decrease observed after 50 cycles.

[0083] Cosolvents and / or fillers

[0084] The liquid electrolyte of the first aspect of the present invention further comprises at least one co-solvent or filler.

[0085] The co-solvents are selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), and propylene sulfite (PS). The following are listed: diethyl sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10, and any mixture thereof.

[0086] In the context of this invention, the term "co-solvent" refers to a substance suitable for dissolving lithium salts in an electrolyte.

[0087] In one particular embodiment, when the electrolyte is characterized by not containing carbonates, the electrolyte does not contain carbonate-based solvents.

[0088] In one particular embodiment, the co-solvent is selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinic anionyl (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFS). A) Ethyl sulfite (ES), propylene sulfite (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and mixtures thereof.

[0089] In a preferred embodiment, the co-solvent is selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof.

[0090] In one particular embodiment, the cosolvent is present in an amount ranging from 1% to 50% by weight relative to the total weight of the electrolyte, preferably from 1% to 40% by weight, more preferably from 1% to 30% by weight, even more preferably from 1% to 20% by weight, and most preferably from 1% to 10% by weight relative to the total weight of the electrolyte.

[0091] In a preferred embodiment:

[0092] The amount of at least one sulfonamide ranges from 5% to 95% by weight of the electrolyte; preferably from 10% to 90% by weight of the electrolyte; more preferably from 30% to 90% by weight of the electrolyte; even more preferably from 50% to 90% by weight of the electrolyte; and most preferably from 70% to 90% by weight of the electrolyte.

[0093] The amount of at least two lithium salts relative to the total weight of the electrolyte can range from 5 wt% to 45 wt%, preferably from 5 wt% to 40 wt%, more preferably from 5 wt% to 25 wt%, even more preferably from 8 wt% to 18 wt%, most preferably from 10 wt% to 15 wt%, and even most preferably about 12 wt%; and,

[0094] The amount of at least one co-solvent relative to the total weight of the electrolyte can range from 1% to 50% by weight, preferably from 1% to 40% by weight, more preferably from 1% to 30% by weight, even more preferably from 1% to 20% by weight, and most preferably from 1% to 10% by weight.

[0095] In the context of this invention, "filler" does not necessarily dissolve lithium salts, but rather provides additional benefits, such as improved wettability of electrodes included in an electrochemical single cell or battery. Examples of fillers are known in the art and include, in particular, fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers.

[0096] In another preferred embodiment:

[0097] The amount of at least one sulfonamide can range from 5% to 95% of the weight of the electrolyte; preferably from 10% to 90% of the weight of the electrolyte; more preferably from 30% to 90% of the weight of the electrolyte; even more preferably from 50% to 90% of the weight of the electrolyte; and most preferably from 70% to 90% of the weight of the electrolyte.

[0098] The amount of at least two lithium salts relative to the total weight of the electrolyte can range from 5 wt% to 45 wt%, preferably from 5 wt% to 40 wt%, more preferably from 5 wt% to 25 wt%, even more preferably from 8 wt% to 18 wt%, most preferably from 10 wt% to 15 wt%, and even most preferably about 12 wt%; and,

[0099] The amount of at least one filler relative to the total weight of the electrolyte can range from 1% to 50% by weight, preferably from 1% to 40% by weight, more preferably from 1% to 30% by weight, even more preferably from 1% to 20% by weight, and most preferably from 1% to 10% by weight.

[0100] Other additives

[0101] In one particular embodiment, the liquid electrolyte of the first aspect of the invention further comprises additives, such as scavengers for HF and water and / or flame retardants.

[0102] In one particular embodiment, the scavenger is lithium hexamethyldisilamide (LiHMDS). This is particularly useful in forming a chemically robust cathode / electrolyte interface (CEI).

[0103] In another specific embodiment, the flame retardant is selected from hexafluorocyclotriphosphazene (HFPN), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), ammonium polyphosphate, melamine polyphosphate, pentaerythritol phosphate, piperazine pyrophosphate, diethyl aluminum hypophosphite, aluminum hypophosphite, aluminum phosphate, calcium borate, zinc borate, magnesium borate, aluminum borate, silica, metakaolin, sepiolite, mica, zeolite, montmorillonite, glass powder, and combinations thereof; preferably hexafluorocyclotriphosphazene (HFPN), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), and combinations thereof.

[0104] advantage

[0105] The electrolyte of the present invention is characterized by its excellent compatibility with Li metal, significantly improved safety, and enhanced performance even at low temperatures due to improved ionic conductivity. Furthermore, the electrolyte of the present invention exhibits significantly lower corrosivity to battery components, thereby extending battery life. Further advantages are described throughout this text (including the Examples section).

[0106] Alternative implementation schemes for electrolytes

[0107] In one particular embodiment, the electrolyte of the present invention comprises:

[0108] i. At least one sulfonamide having the general formula I,

[0109]

[0110] in

[0111] R1 and R2 are each independently selected from linear or branched C1-C atoms that can be substituted by one or more fluorine atoms. 12 Alkyl groups, linear or branched C2-C atoms that may be substituted with one or more fluorine atoms. 12 Alkenyl groups, C6-C atoms that can be substituted with one or more fluorine atoms 12 Aryl groups, and CH2CH2O-(CH2CH2O) n -R3, where R3 is methyl or ethyl, and n is an integer from 0 to 20; or R1 and R2 may combine with each other to form a nitrogen-containing aliphatic ring;

[0112] ii. A combination of at least two lithium salts, wherein the at least two lithium salts are selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF2H)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(SO2CHF2)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3;

[0113] iii. At least one co-solvent, said at least one co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Propylene phosphate (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10, and any mixture thereof; and

[0114] iv. Optionally, the filler is selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers;

[0115] Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

[0116] In a preferred embodiment, the electrolyte of the present invention comprises:

[0117] i. At least one sulfonamide having the general formula I,

[0118]

[0119] in

[0120] -R1 and R2 are each independently selected from linear C1-C3 alkyl, C2-C3 alkenyl and -CH2CH2O-CH3;

[0121] ii. A combination of at least two lithium salts, wherein the at least two lithium salts are selected from LiN(SO2F)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)2 and LiBF2(C2O4);

[0122] iii. At least one co-solvent, said at least one co-solvent being selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof; and

[0123] iv. Optionally, the filler is selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers;

[0124] Furthermore, the liquid electrolyte does not contain organic carbonates.

[0125] In a more preferred embodiment, the electrolyte of the present invention comprises:

[0126] i. N,N-Dimethylaminosulfonyl fluoride;

[0127] ii. Combinations of lithium salts LiFSI and LiBF2(C2O4); and

[0128] iii. At least one co-solvent, said at least one co-solvent being selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof; and

[0129] iv. Optionally, the filler is selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers;

[0130] Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

[0131] In yet another preferred embodiment, the electrolyte of the present invention comprises:

[0132] i. N,N-Dimethylaminosulfonyl fluoride;

[0133] ii. Combinations of lithium salts LiFSI and LiBF2(C2O4); and

[0134] iii. At least one filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers; and

[0135] iv. Optionally, a co-solvent selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof;

[0136] Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

[0137] Electrochemical single cell and battery

[0138] The electrolyte of the first aspect of the invention is particularly suitable for electrochemical devices such as electrochemical single-cell batteries or cells, especially secondary electrochemical single-cell batteries or cells in which the battery reaction is reversible.

[0139] The second aspect of the invention relates to an electrochemical single-cell battery or cell comprising a liquid electrolyte according to the first aspect of the invention.

[0140] In a preferred embodiment, the second aspect of the invention relates to an electrochemical single-cell battery or cell comprising an electrolyte according to any, preferred or particular embodiment of the first aspect of the invention as defined above, and further comprising a negative electrode, a positive electrode and optional separators.

[0141] In a preferred embodiment, a second aspect of the invention relates to a lithium metal battery comprising an electrolyte according to any embodiment of the first aspect of the invention as defined above. A lithium metal battery is characterized by comprising a negative electrode composed substantially of metallic lithium.

[0142] In another preferred embodiment, a second aspect of the invention relates to a lithium metal battery comprising a positive electrode, wherein the positive electrode material is selected from lithium manganese oxide, lithium nickel oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese oxide, lithium manganese cobalt oxide, lithium copper oxide, lithium copper sulfide, lithium iron phosphate, lithium iron sulfide, lithium manganese iron phosphate, and lithium nickel cobalt aluminum oxide.

[0143] In another preferred embodiment, a second aspect of the invention relates to a lithium metal battery comprising a positive electrode, wherein the positive electrode material is a lithium nickel manganese cobalt oxide, such as LiNi. 0.6 Mn 0.2 Co 0.2 O2 (NMC622), lithium iron phosphate LiFePO4 (LFP) and lithium manganese iron phosphate LiFe x Mn 1-x PO4, where x < 1 (LMFP). In a more preferred embodiment, the positive pole is LFP.

[0144] The positive electrode may additionally contain other additives, such as conductive carbon and polymer binders. In one embodiment, the positive electrode also contains conductive carbon selected from carbon black (e.g., Super P®), carbon nanotubes, and mixtures thereof. In another particular embodiment, the positive electrode also contains polyvinylidene fluoride (PVdF) as a polymer binder. Preferably, the weight ratio of LFP:conductive carbon:polymer binder is about 96.5:1.5:2.

[0145] In another preferred embodiment, a second aspect of the invention relates to a lithium metal battery, which further includes a separator, preferably a porous separator, arranged in such a configuration between at least one electrode and an electrolyte that lithium cations can flow through the separator between the electrolyte and the surface of the at least one electrode.

[0146] Examples of suitable separators are known to those skilled in the art and include polypropylene membranes (preferably microporous polypropylene membranes) or ceramic materials. A preferred separator is Celgard® H2010 (a 20 µm three-layer microporous membrane PP / PE / PP).

[0147] In a specific embodiment, the thickness of the separator is from 1 µm to 50 µm, preferably from 15 µm to 35 µm, and more preferably about 20 µm. The porosity of the separator can also vary within a specific range, particularly, the average pore size is from 0.001 µm to 0.100 µm, preferably from 0.020 µm to 0.080 µm, and more preferably about 0.064 µm.

[0148] In one particular embodiment, the electrochemical cell of the first aspect of the present invention includes a negative electrode, preferably a lithium metal negative electrode.

[0149] In another preferred embodiment, the electrochemical cell or lithium metal battery of the second aspect of the present invention has low resistance at the interface between the electrolyte and the lithium metal electrode. Specifically, the interface resistance can be determined by measuring the electrochemical impedance spectroscopy (EIS) of the electrochemical cell or lithium metal battery using a potentiostat. More specifically, at 25°C at 10... 6 Hz to 10 -2 Electrochemical impedance spectroscopy was recorded in the Hz range. According to any of the above embodiments, the electrochemical impedance of the electrochemical cell or lithium metal battery is less than 100 Ω cm⁻¹. 2 Preferably below 75 Ω cm 2 More preferably below 50 Ω cm 2 Even more preferably about 35 Ω cm 2 .

[0150] Applications of the electrochemical battery of the present invention

[0151] The electrochemical battery of the present invention can be applied to various electronic devices, including but not limited to: electric motors; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; light electric vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; power storage systems; and so on.

[0152] Methods for preparing electrolytes

[0153] In a fourth aspect, the present invention relates to a method for preparing a liquid electrolyte, comprising the following steps:

[0154] (i) Provide a combination of at least two lithium salts;

[0155] (ii) Mix at least one sulfonamide of formula I with the salt of step (i);

[0156] (iii) Add at least:

[0157] a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Propyl phosphate (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamide with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or

[0158] b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers; and

[0159] (iv) The mixture obtained by stirring.

[0160] In one particular embodiment, steps (i) and (ii) of the above method can be performed using pure components of the electrolyte (e.g., pure solids or liquids), or alternatively, the components can be dissolved in at least one solvent before or after mixing. At least one co-solvent is particularly necessary when the mixture of sulfonamide and lithium salt of formula (I) is a solid or contains solid particles (e.g., suspensions or precipitates).

[0161] Preferably, the mixture obtained from step (iii) is stirred for a certain period of time to ensure a homogeneous solution (i.e., no suspended matter is visible). Stirring is performed magnetically at 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, and 1000 rpm; preferably, stirring is performed in the range of 100 rpm to 500 rpm, and even more preferably at about 300 rpm. Furthermore, the mixture from step (iii) is stirred for at least 5 minutes, at least 15 minutes, at least 30 minutes, at least 1 hour, at least 2 hours, at least 4 hours, at least 6 hours, at least 12 hours, or at least 1 day; preferably, the mixture from step (iii) is stirred for 1 hour to 4 hours, more preferably 2 hours.

[0162] All steps of the above method are performed at a temperature of 10°C to 30°C, preferably 15°C to 25°C, and even more preferably 20°C to 25°C (room temperature).

[0163] Method for preparing an electrochemical single-cell battery or battery containing the electrolyte

[0164] The method for preparing the electrochemical cell of the present invention will be apparent to those skilled in the art using common general knowledge. Another aspect of the invention relates to the method, which includes the following steps:

[0165] (i) Providing a positive electrode for an electrochemical single cell or battery;

[0166] (ii) Provide a negative electrode for an electrochemical single cell or battery;

[0167] (iii) Providing a liquid electrolyte as defined above or in any preferred or particular embodiment of the first aspect of the invention; and

[0168] (iv) The surfaces of the positive electrode provided in step (i) and the negative electrode provided in step (ii) are coated with the electrolyte provided in step (iii) in such a manner that the electrolyte is arranged between the positive and negative electrodes so that lithium cations can flow from the positive electrode to the negative electrode, said surfaces optionally being covered with porous separators before being coated with the electrolyte.

[0169] In a particular embodiment, the provision of the positive electrode in step (i) includes preparing a slurry in a solvent such as N-methyl-2-pyrrolidone and casting it onto a suitable substrate such as an aluminum current collector.

[0170] In one particular embodiment, the coating step (iv) is performed using a casting technique as known in the art. As described above, such a surface can be covered with a porous separator. Preferably, such a porous separator is a polymer separator, more preferably a polypropylene separator.

[0171] Preferred materials for preparing electrochemical single-cell batteries or batteries are as defined in the preferred and specific embodiments of the electrochemical batteries described above.

[0172] Example

[0173] The following examples are intended to illustrate, but are not intended to limit, the disclosed implementations.

[0174] List of abbreviations

[0175] FSA11: Dimethylaminosulfonyl fluoride

[0176] Triethylene glycol dimethyl ether: Triethylene glycol dimethyl ether

[0177] LiFSI: Lithium bis(fluorosulfonyl)imide (LiN(SO2F)2)

[0178] LiDFOB: Lithium difluoro(oxalate)borate (LiBF2(C2O4))

[0179] LiPF6: Lithium hexafluorophosphate

[0180] EC: Ethylene carbonate

[0181] FEC: Ethylene fluorocarbonate

[0182] rpm: revolutions per minute

[0183] RT: Room temperature

[0184] Reagents and starting materials

[0185] The following chemicals were purchased from Sigma-Aldrich, Chemfish, TCI, and dried under vacuum (70°C if necessary) and / or with molecular sieves before use.

[0186] Example 1: Preparation of Electrolytes

[0187] Five electrolytes having the compositions (in weight %) disclosed in the table below were prepared according to the following general steps.

[0188] Electrolyte 1 (E1) (Comparison)

[0189] Weigh LiFSI into a vial and add FSA11 in an appropriate amount. Stir the resulting mixture at 300 rpm and room temperature for about 2 hours.

[0190] Electrolyte 2 (E2) (according to the present invention)

[0191] In the first step, LiDFOB was weighed into a vial, and the corresponding amount of triethylene glycol dimethyl ether was added. The mixture was stirred at 300 rpm and room temperature for 10 minutes. Next, LiFSI was weighed and FSA11 was added. The resulting mixture was stirred at 300 rpm and room temperature for approximately 2 hours.

[0192] Electrolyte 3 (E3) (Comparison)

[0193] In the first step, LiDFOB was weighed into a vial, and the corresponding amount of EC was added. The mixture was stirred at 300 rpm and room temperature for 10 minutes. Next, LiFSI was weighed and FSA11 was added. The resulting mixture was stirred at 300 rpm and room temperature for approximately 2 hours.

[0194] Electrolyte 4 (E4) (Comparison)

[0195] In the first step, LiDFOB was weighed into a vial, and the corresponding amount of FEC was added. The mixture was stirred at 300 rpm and room temperature for 10 minutes. Next, LiFSI was weighed and FSA11 was added. The resulting mixture was stirred at 300 rpm and room temperature for approximately 2 hours.

[0196] The final electrolyte composition is as follows:

[0197]

[0198] Example 2: Preparation of Electrochemical Cells

[0199] A lithium metal battery containing the electrolyte of Example 1 was prepared according to the following steps:

[0200] Cathode Preparation: The LiFePO4 cathode consisted of 96.5 wt% LFP (Y7 from Hunan Yuneng), 1.5 wt% conductive carbon (containing 1.0% Super P carbon and 0.5% carbon nanotubes), and 2 wt% polymer binder (PVdF). A slurry was prepared using N-methyl-2-pyrrolidone (NMP) as a solvent and, after homogenization, cast onto a 12 µm thick aluminum current collector. Finally, it was dried overnight under vacuum at 80°C to 120°C to achieve an average loading of approximately 2.3 mAh / cm³. -2 .

[0201] The negative electrode is provided with lithium metal foil (China Energy Lithium, 14 mm in diameter and 50 µm in thickness).

[0202] Battery Assembly: In an argon-filled glove box, a coin cell was assembled using the LFP (12 mm diameter) positive electrode as defined above, Celgard® H2010 (20 µm three-layer microporous membrane PP / PE / PP) as a separator, and a Li metal disk as the negative electrode. The liquid electrolyte prepared according to Example 1 was injected between the positive electrode and the separator.

[0203] Example 3: Electrochemical Measurement

[0204] The batteries prepared as described in Example 2 were subjected to constant current cycling at a range of 2.8 V to 3.65 V relative to Li / Li+ using a Maccor battery tester (4000 series). The applied scheme was based on one cycle at a current of C / 10, followed by constant cycling at C / 2–D / 2 at 25°C.

[0205] Figure 1 The capacity retention of Li°||LFP batteries containing the following electrolytes at 25 °C with respect to cycle number is shown: a) a mixture of 1.0 M LiFSI lithium salts in FSA11 (E1); b) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / triethylene glycol dimethyl ether at a 90 / 10 vol% solvent ratio (E2); c) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / EC at a 90 / 10 vol% solvent ratio (E3); and d) LiFSI / LiDFOB lithium salts with molar concentrations of 0.95 M and 0.05 M in FSA11 / FEC at a 90 / 10 vol% solvent ratio (E4).

[0206] exist Figure 1 The diagram shows that, compared to the capacity retention of an electrolyte (E1) containing only one lithium salt and no cosolvent used as a reference, the electrolyte (E2) according to the invention, comprising a mixture of two lithium salts and a cosolvent, exhibits better capacity retention. After 75 cycles, both E1 and E2 reached 124 mAh g⁻¹. -1 and 141 mAh g -1 Specific capacity.

[0207] It can also be seen that, compared to carbonate-free electrolytes, the incorporation of carbonate as a co-solvent in comparative electrolytes E3 and E4 adversely affects cycleability, leading to significant capacity decay after 50 cycles. Without being bound by any theory, the addition of carbonate appears to affect the SEI formed on the negative electrode side. At the end of cycling, the coulombic efficiency of the cycled battery with carbonate is lower than that without carbonate, indicating more side reactions occurring on the negative electrode side. After approximately 55 cycles, the internal resistance of the battery increases to a value that prevents further cycling.

Claims

1. A liquid electrolyte, comprising: i. At least one sulfonamide having the general formula I, ， in - R1and R2are each independently selected from linear or branched C1-C 12 alkyl, linear or branched C2-C 12 alkenyl which can be substituted with one or more fluorine atoms, C6-C 12 aryl which can be substituted with one or more fluorine atoms, and CH2CH2O-(CH2CH2O) n - R3, wherein R3is a methyl or ethyl group, and n is an integer from 0 to 20; or R1and R2may be combined with each other to form a nitrogen-containing aliphatic ring; ii. A combination of at least two lithium salts selected from LiClO4, LiNO3, LiBF4, LiAsF6, LiPF6, LiBF3Cl, LiF, LiN(SO2F)2, LiN(SO2CF2H)2, LiN(SO2CF3)2, LiN(SO2CF3)(SO2CF2H), LiN(SO2CF3)(SO2F), LiN(SO2CHF2)(SO2F), LiN(C2F5SO2)(SO2F), LiB(C2O4)2, LiBF2(C2O4), LiC(SO2CF3)3, LiPF3(C2F5)3, and LiCF3SO3; and iii. At least, a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Acetamides with the chemical structure R1CONR2R3, including propyl ester (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamides with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers; Furthermore, the liquid electrolyte described therein does not contain organic carbonates.

2. The liquid electrolyte according to claim 1, wherein R1 and R2 in the at least one sulfonamide having general formula I are each independently selected from linear C1-C6 alkyl, C2-C6 alkenyl and -CH2CH2OCH2CH2O-CH3; or R1 and R2 can be combined with each other to form a 3- to 6-membered nitrogen-containing aliphatic ring.

3. The liquid electrolyte according to claim 1, wherein the at least one sulfonamide accounts for 5% to 95% of the weight of the liquid electrolyte, preferably 30% to 90% of the weight of the electrolyte, more preferably 50% to 90% of the weight of the electrolyte; and even more preferably 70% to 90% of the weight of the electrolyte.

4. The liquid electrolyte according to claim 1, wherein the combination of at least two lithium salts is selected from LiN(SO2F)2, LiN(SO2CF3)(SO2CF2H), LiB(C2O4)2, LiBF2(C2O4), LiN(SO2CF3)2, LiN(SO2CF3)(SO2F), LiN(SO2F)(SO2CF2H), preferably LiN(SO2F)2 and LiBF2(C2O4).

5. The liquid electrolyte according to claim 1, wherein the amount of the at least two lithium salts ranges from 5% to 45% by weight, preferably from 5% to 25% by weight, more preferably from 8% to 18% by weight, and even more preferably from 10% to 15% by weight, relative to the total weight of the electrolyte.

6. The liquid electrolyte according to claim 1, wherein the at least one co-solvent is present, and the at least one co-solvent is selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof.

7. The liquid electrolyte according to claim 1, wherein the electrolyte further comprises: - At least one cleaning agent selected from lithium hexamethyldisilamide (LiHMDS); and / or - At least one flame retardant, wherein the at least one flame retardant is selected from hexafluorocyclotriphosphazene (HFPN), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), ammonium polyphosphate, melamine polyphosphate, pentaerythritol phosphate, piperazine pyrophosphate, diethyl aluminum hypophosphite, aluminum hypophosphite, aluminum phosphate, calcium borate, zinc borate, magnesium borate, aluminum borate, silica, metakaolin, sepiolite, mica, zeolite, montmorillonite, glass powder, and combinations thereof, preferably hexafluorocyclotriphosphazene (HFPN), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), and combinations thereof.

8. The liquid electrolyte according to claim 1, comprising: i. N,N-Dimethylaminosulfonyl fluoride; ii. Combinations of lithium salts LiFSI and LiBF2(C2O4); and iii. At least one cosolvent selected from triethylene glycol dimethyl ether, ethylene sulfite, and mixtures thereof; The liquid electrolyte described herein does not contain organic carbonates.

9. The liquid electrolyte according to claim 1, wherein the at least one filler is present, and the at least one filler is selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ether.

10. An electrochemical single-cell battery or cell, comprising a liquid electrolyte according to any one of claims 1 to 9, a positive electrode, a negative electrode, and optionally a separator.

11. The electrochemical single-cell battery or battery according to claim 10, wherein the positive electrode is selected from lithium iron phosphate LiFePO4 (LFP) and lithium manganese iron phosphate LiFe. x Mn 1-x PO4, where x < 1 (LMFP).

12. The electrochemical single-cell battery or battery according to claim 10, comprising a negative electrode selected from lithium metal.

13. The use of any one of the electrochemical single cell or battery according to claims 10 to 12 in the following: electric motor; electric vehicle, including electric vehicle (EV), hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV), etc.; light electric vehicle, including electric bicycle (E-bike) and electric scooter (E-scooter); electric golf cart; or power storage system.

14. A method for preparing a liquid electrolyte according to any one of claims 1 to 9, comprising the following steps: (i) Provide a combination of at least two lithium salts; (ii) Mix at least one sulfonamide of formula I with the salt of step (i); (iii) Add at least: a. A co-solvent, said co-solvent being selected from 1,2-bis(2,2-difluoroethoxy)ethane (DF2EO), dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (triethylene glycol dimethyl ether), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), tetrahydropyran (THP), γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran, diethyl ether, methyl-tert-butyl ether, succinate (SN), glutaronitrile (GN), adiponitrile (AN), N,N-dimethyltrifluoromethane-sulfonamide (TFSA), N,N-dimethyldifluoromethane-sulfonamide (DFSA), ethylene sulfite (ES), sulfite Acetamides with the chemical structure R1CONR2R3, including propyl ester (PS), diethylene sulfite (DES), dimethyl sulfite (DMS), triethyl phosphate (TEP), difluoroethyl acetate (DFEA), methyl difluoroacetate (MDFA), 2-(2,2,2-trifluoroethoxy)ethyl methyl ether (TEME), 2-methoxyethoxy-2,2-difluoroethyl ether (MDFE), triethyl phosphate (TEP), trimethyl phosphate (TMP), tripropyl phosphate (TPP), methyl formate (MF), methyl acetate (MA), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), trimethylsilyl propane sulfonate (TMSP), and acetamides with the chemical structure R1CONR2R3, wherein R1 can be F, CF3, CF2H, or CFH2, and R2 and R3 can independently be H, –(CH2). n CH3, –(CH2) n CF3、–(CH2) n F, or –(CH2) n CH2F or –(CH2) n CHF2, where n = 1 to 10; and / or b. A filler selected from fluorobenzene (FPh), 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, anisole, fluoroanisole, tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (D2), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and polyoxyethylene alkyl ethers; and (iv) The mixture obtained by stirring.

15. A method for preparing an electrochemical single-cell battery or battery according to any one of claims 10 to 12, comprising the following steps: (i) Providing a positive electrode for an electrochemical single cell or battery; (ii) Provide a negative electrode for an electrochemical single cell or battery; (iii) Providing a liquid electrolyte according to any one of claims 1 to 13; and (iv) The electrolyte provided in step (iii) is used to coat the surfaces of the positive electrode provided in step (i) and the negative electrode provided in step (ii) in such a manner that lithium cations can flow from the positive electrode to the negative electrode. The surfaces are optionally covered with porous separators before being coated with the electrolyte.

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