A non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device.

Abstract

This invention provides a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. The non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent, and functional additives, wherein the functional additives include a bis(sulfinyl) ester structure as shown in Formula I. When used in a lithium-ion battery, the non-aqueous electrolyte of this invention effectively enhances the wettability of the electrolyte, increases its ionic conductivity, improves its low-temperature discharge capability, and enhances its stability under high-temperature and high-voltage conditions, thereby improving the discharge capability and lifespan of the lithium-ion battery during high-temperature storage and high-temperature cycling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a non-aqueous electrolyte, a lithium ion battery, a battery module, a battery pack and a power utilization device. BACKGROUND

[0002] With the rapid development of domestic new energy industry, the demand for power batteries and energy storage batteries in the new energy industry has been further improved, and the demand for developing lithium ion batteries with high energy density, long cycle, wide temperature range, high power density and green and safe environmental protection is increasing. Therefore, in view of one or several of the above problems, a more suitable electrolyte formula and a new type of electrolyte additive are designed, so that the comprehensive performance of the battery is further improved.

[0003] The use temperature range of the battery is generally 0-40 degrees Celsius. When the battery is at a lower space temperature, the viscosity of the electrolyte increases, the ion conductivity is inhibited, the internal impedance of the battery is increased, and the discharge capacity of the battery is affected. How to improve the low-temperature discharge capacity of the battery has become an important topic of discussion. Therefore, it is particularly important to develop and design a lithium ion battery with a wider temperature range.

[0004] Based on this, the present application designs a new type of electrolyte additive and reasonably matches the lithium salt, the solvent and the additive, and designs a lithium ion battery non-aqueous electrolyte with optimized low-temperature performance, so that the lithium ion battery has excellent low-temperature discharge performance and cycle performance. SUMMARY

[0005] In view of the shortcomings of the prior art described above, the purpose of the present application is to provide a non-aqueous electrolyte, a lithium ion battery, a battery module, a battery pack and a power utilization device. When the non-aqueous electrolyte is used in a lithium ion battery, it can effectively enhance the wettability of the electrolyte, improve the ionic conductivity of the electrolyte, improve the low-temperature discharge capacity of the electrolyte, improve the stability of the electrolyte under high temperature and high voltage conditions, and thus improve the discharge capacity and service life of the lithium ion battery under high temperature storage and high temperature cycle.

[0006] To achieve the above-mentioned purpose and other related purposes, the first aspect of the present application provides a non-aqueous electrolyte, which comprises a lithium salt, a non-aqueous organic solvent and a functional additive, the functional additive comprises a bis-sulfinyl ester structure represented by Formula I,

[0007] ;

[0008] Wherein, M is selected from substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocyclylene, substituted or unsubstituted arylene, and substituted or unsubstituted heteroarylene.

[0009] The second aspect of the present application provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and the non-aqueous electrolyte of the first aspect of the present application.

[0010] The third aspect of the present application provides a battery module comprising the lithium ion battery of the second aspect of the present application.

[0011] The fourth aspect of the present application provides a battery pack comprising the battery module of the third aspect of the present application.

[0012] The fifth aspect of the present application provides an electric device comprising the lithium ion battery of the second aspect of the present application, wherein the lithium ion battery is used as a power supply of the electric device, and the electric device comprises a mobile device, an electric vehicle, an electric tool, an electric train, a satellite, a ship, and an energy storage system.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] (1) The compound having the structure shown in Formula I is used as an electrolyte additive in the present application, which has good wettability and can increase the interaction between the electrolyte and the electrode, so that the electrolyte can perform more effective ion transmission at a lower temperature. Better wettability also has a positive effect on desolvation during the embedding process of lithium ions from the electrolyte to the electrode sheet, and has a positive effect on inhibiting the generation of dead lithium. The symmetry of the compound itself also has a positive effect on the dissolution of lithium salt and other organic solvents.

[0015] (2) The compound having the structure shown in Formula I has a sulfinyl functional group, which has a high reduction potential and can form a thin and stable electrolyte interface (SEI film) at the negative electrode in preference to the solvent. The formation of a sulfur-containing SEI film has a positive effect on improving the thermal stability and chemical stability of the interface. In combination with other additives, the reduction potential of other additives can be adjusted, the film formation reaction of other additives can be inhibited, and the effect of improving the overall stability of the battery and increasing the cycle performance and service life of the battery can be achieved. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the non-aqueous electrolyte, the lithium ion battery, the battery module, the battery pack, and the electric device provided by the present application will be described in detail.

[0017] "RANGES" disclosed herein are defined by a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, the selected lower limit and upper limit defining the boundaries of a particular range. Ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Further, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, "0-5" is merely a shorthand for these numerical combinations. Also, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0018]

Non-aqueous electrolyte solution

[0019] The first aspect of the present application provides a non-aqueous electrolyte solution comprising a non-aqueous organic solvent, a lithium salt, and a functional additive, wherein the functional additive comprises a bis-sulfinic ester structure represented by Formula I,

[0020]

[0021] wherein M is selected from substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted unsaturated hydrocarbylene, substituted or unsubstituted heterocyclylene, substituted or unsubstituted arylene, and substituted or unsubstituted heteroarylene.

[0022] In some embodiments, M is selected from substituted or unsubstituted alkylene, which can be optionally substituted or unsubstituted C1-C30 alkylene, substituted or unsubstituted C1-C20 alkylene, substituted or unsubstituted C1-C10 alkylene, substituted or unsubstituted C1-C8 alkylene, substituted or unsubstituted C1-C6 alkylene, and substituted or unsubstituted C1-C4 alkylene. Alkylene includes, but is not limited to, methylene, ethylene, n-propylene, i-propylene, n-butylene, i-butylene, t-butylene, sec-butylene, and the like. Substituents include, but are not limited to, deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0023] In some embodiments, M is selected from substituted or unsubstituted cycloalkylene. Cycloalkylene groups that can optionally be substituted or unsubstituted include C3-C30 cycloalkylene, C3-C20 cycloalkylene, C3-C10 cycloalkylene, C3-C8 cycloalkylene, C3-C6 cycloalkylene, C3-C4 cycloalkylene, and the like. Cycloalkylene groups include, for example, cyclopropylene, cyclobutylene, cyclopentylene, cyclopentenylene, cyclohexylene, cyclohexenylene. Substituents that can optionally be present include, for example, deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0024] In some embodiments, M is selected from substituted or unsubstituted heterocyclylene. Heterocyclylene groups that can optionally be substituted or unsubstituted include azetidinylene, azetidinidene, azetidinylene, pyrrolidinylene, imidazolidinylene, pyrazolidinylene, and the like. Substituents that can optionally be present include, for example, deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0025] In some embodiments, M is selected from substituted or unsubstituted heterocyclylene. Heterocyclylene groups that can optionally be substituted or unsubstituted include azetidinylene, azetidinidene, azetidinylene, pyrrolidinylene, imidazolidinylene, pyrazolidinylene, and the like. Substituents that can optionally be present include, for example, deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0026] In some embodiments, M is selected from substituted or unsubstituted arylene, optionally substituted or unsubstituted C6-C60 arylene, substituted or unsubstituted C6-C50 arylene, substituted or unsubstituted C6-C40 arylene, substituted or unsubstituted C6-C30 arylene, substituted or unsubstituted C6-C30 arylene, substituted or unsubstituted C6-C15 arylene, substituted or unsubstituted C6-C12 arylene. Wherein the substituents are optionally selected from deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide group, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0027] In some embodiments, M is selected from substituted or unsubstituted heteroarylene, optionally substituted or unsubstituted C6-C60 heteroarylene, substituted or unsubstituted C6-C50 heteroarylene, substituted or unsubstituted C6-C40 heteroarylene, substituted or unsubstituted C6-C30 heteroarylene, substituted or unsubstituted C6-C30 heteroarylene, substituted or unsubstituted C6-C15 heteroarylene, substituted or unsubstituted C6-C12 heteroarylene. Wherein the substituents are optionally selected from deuterium, hydroxyl, amino, thiol, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide group, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0028] In some specific embodiments, M is selected from substituted or unsubstituted arylene, substituted or unsubstituted heteroarylene.

[0029] In some specific embodiments, M is selected from unsubstituted arylene, unsubstituted heteroarylene.

[0030] In some preferred embodiments, M is selected from phenyl, furan, thiophene, pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, pyrimidine.

[0031] In some specific embodiments of the present application, the bis-sulfonate ester structure of Formula I is selected from any one or more of the following structures:

[0032] ;

[0033] ;

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] .

[0039] The compound with the structure shown in Formula I is used as an electrolyte additive, has good wettability itself, can increase the interaction between the electrolyte and the electrode, so that the electrolyte can perform more effective ion transmission under lower temperature conditions; better wettability also has a positive effect on desolvation during the process of lithium ion embedding from the electrolyte to the electrode sheet, and has a positive effect on inhibiting the generation of dead lithium. The symmetry of the compound itself also has a positive effect on the dissolution of lithium salt and other organic solvents.

[0040] In the non-aqueous electrolyte provided by the application, the mass proportion of the double-sulfinyl ester structure shown in Formula I in the non-aqueous electrolyte is 0.5% to 4%. In some embodiments, the mass proportion of the double-sulfinyl ester structure shown in Formula I in the non-aqueous electrolyte may, for example, be 0.5% to 1%, 1% to 3%, 3% to 4%, 0.5% to 3%, 0.5% to 2%, 2% to 4%, etc. Alternatively, the mass proportion of the double-sulfinyl ester structure shown in Formula I in the non-aqueous electrolyte is 0.5% to 3%. Within the above range, the additive can exert its maximum effect in this interval. If the content is too low outside the range, the effect is insufficient, and if the content is too high, the battery impedance will increase, thereby affecting the battery performance.

[0041] The non-aqueous electrolyte provided by the application further comprises other additives, wherein the other additives are selected from the group consisting of one or more of fluoroethylene carbonate, difluoroethylene carbonate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)borate, lithium bisfluorosulfonylimide, tetravinylsilane, lithium trifluoromethylsulfonate, lithium fluorosulfate, lithium sulfamate, lithium tetrafluoroborate, methylene methanedisulfonate, N-methyl bis(fluorosulfonyl)imide, vinylene carbonate, ethylene sulfate, dimethyl sulfate, 4,5-dicyano-2-methylimidazole, and 4,5-dicyano-2-ethylimidazole. Preferably, the other additives are selected from the group consisting of one or more of lithium bisfluorosulfonylimide, lithium fluorosulfate, vinylene carbonate, fluoroethylene carbonate, and lithium tetrafluoroborate, and more preferably, the other additives are selected from the group consisting of lithium bisfluorosulfonylimide and vinylene carbonate. The compound having the functional group part of sulfinyl group shown in Formula I is used in the application, which has a higher reduction potential and can form a thin and stable SEI film at the negative electrode in preference to the solvent. The formation of the SEI film containing sulfur is beneficial to improving the thermal stability and chemical stability of the interface. In combination with other additives, the reduction potential of the other additives can be adjusted, the film formation reaction of the other additives can be inhibited, and the other additives can be protected, so that the stability of the battery as a whole can be improved, and the cycle performance and service life of the battery can be increased.

[0042] In the non-aqueous electrolyte provided by the application, the mass ratio of the other additives in the non-aqueous electrolyte is 1.5% to 5%. In some embodiments, the mass ratio of the other additives in the non-aqueous electrolyte may, for example, be 1.5% to 2%, 2% to 3%, 3% to 5%, 2% to 4%, or 4% to 5%. In some embodiments, the mass ratio of the other additives in the non-aqueous electrolyte is 1.5% to 3%. Within the above range, the additive can play a coordinating role to the greatest extent, and the performance of the battery can be improved. Outside the range, the stability of the SEI film of the battery can be affected, and the performance of the battery can be deteriorated.

[0043] In the non-aqueous electrolyte provided by the application, the lithium salt is selected from the group consisting of one or more of lithium hexafluorophosphate, lithium bisfluorosulfonyl oxide phosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium bisfluorosulfonyl oxide borate, lithium aluminum chloride, lithium bisoxalate borate, lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethylsulfonate, and lithium bis(trifluoromethylsulfonate)imide.

[0044] In the non-aqueous electrolyte provided by this invention, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. In some embodiments, the content of the lithium salt in the non-aqueous electrolyte can also be 0.5 mol / L to 1 mol / L, 1 mol / L to 1.5 mol / L, 1.5 mol / L to 2 mol / L, 2 mol / L to 2.5 mol / L, etc. Within the above range, high lithium-ion conductivity and stable lithium-ion transport can be guaranteed. If the proportion of the lithium salt is too high (the content in the non-aqueous electrolyte is higher than 2.5 mol / L), it will lead to incomplete lithium salt dissociation, excessive electrolyte viscosity, which will hinder lithium-ion transport and reduce rate performance and low-temperature performance. If the proportion of the lithium salt is too low (the content in the non-aqueous electrolyte is lower than 0.5 mol / L), it will lead to poor electrochemical stability of the electrolyte.

[0045] In the non-aqueous electrolyte provided by this invention, the non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates. In some embodiments, the non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, ethyl gamma-butyrolactone, propyl propionate, methyl acetate, and ethyl propionate.

[0046] In the non-aqueous electrolyte provided by this invention, the non-aqueous organic solvent accounts for 71% to 91% of the electrolyte by mass. In some embodiments, the non-aqueous organic solvent may also account for 71% to 75%, 75% to 84%, 85% to 91%, etc. Within the above ranges, lithium salts and additives can be dissolved well. If the proportion of the non-aqueous organic solvent is too high (more than 91% by mass in the non-aqueous electrolyte), the electrochemical stability of the electrolyte will be poor. If the proportion of the non-aqueous organic solvent is too low (less than 75% by mass in the non-aqueous electrolyte), the lithium salt will not dissociate completely, and the electrolyte viscosity will be too high.

[0047] Lithium-ion batteries

[0048] A second aspect of the present invention provides a lithium-ion battery, the lithium-ion battery further comprising a positive electrode, a negative electrode, a separator, and a lithium-ion battery electrolyte, wherein the lithium-ion battery electrolyte is selected from the lithium-ion battery electrolyte of the first aspect of the present invention.

[0049] The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as a metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The positive electrode active material layer includes a positive electrode active material selected from one or more combinations of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium iron manganese phosphate. The positive electrode active material layer may also include a conductive agent and a binder. The positive electrode active material used in this experiment is selected from lithium nickel cobalt manganese oxide. Those skilled in the art can choose conductive agents and binders suitable for lithium-ion batteries. The conductive agent may include, for example, at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The adhesive may include, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0050] In some embodiments, the positive electrode can be prepared by dispersing the above-mentioned components for preparing the positive electrode, such as the positive electrode material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode after drying, cold pressing and other processes.

[0051] The negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as a metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The negative electrode active material layer includes a negative electrode active material selected from one or more combinations of silicon-carbon, silicon-carbon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal. The negative electrode active material layer may also include a plasticizer, a conductive agent, and a binder. The negative electrode active material used in this experiment may be selected from artificial graphite. Those skilled in the art may select plasticizers, conductive agents, and binders suitable for lithium-ion batteries. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS), and sodium carboxymethyl cellulose (CMC-Na).

[0052] In some embodiments, the negative electrode can be prepared by dispersing the components used to prepare the negative electrode, such as the negative electrode material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode after drying, cold pressing and other processes.

[0053] The lithium-ion battery provided in the second aspect of this invention can be prepared using methods known in the art. For example, a positive electrode, a separator, and a negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes, and then the layers are stacked to obtain a bare cell; the bare cell is placed in an outer packaging shell, dried, and then injected with lithium-ion battery electrolyte, and after vacuum sealing, settling, formation, and shaping processes, a lithium-ion battery is obtained.

[0054] Battery Module

[0055] A third aspect of the present invention provides a battery module comprising any one or more lithium-ion batteries described in the second aspect of the present invention. The number of lithium-ion batteries in the battery module can be adjusted according to the application and capacity of the battery module.

[0056] Battery Pack

[0057] A fourth aspect of the present invention provides a battery pack comprising any one or more battery modules described in the third aspect of the present invention. That is, the battery pack comprises any one or more lithium-ion batteries described in the second aspect of the present invention.

[0058] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0059] Electrical appliances

[0060] A fifth aspect of the present invention provides an electrical device comprising any one or more lithium-ion batteries described in the second aspect of the present invention. The lithium-ion batteries can be used as a power source for the electrical device. Preferably, the electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0061] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0062] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Unless otherwise specified, specific experimental or operational conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0063] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0064] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0065] Example 1

[0066] Electrolyte preparation: The electrolyte was prepared in a dry room (environmental dew point below -40℃). Ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC) were mixed in a volume ratio of 5:2:3 as an organic solvent, and a total of 100 mL was prepared. Lithium salt LiPF6 was added to this solvent to achieve a molar concentration of 1.1 M / L. Then, 1% of Compound 1, 1% of lithium bisfluorosulfonyl imide (1% LiFSI), and 1% of ethylene carbonate (1% VC) were added according to the total mass of the above electrolyte. The mixture was stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Example 1. The prepared electrolyte was injected into a pouch cell, and after standing, formation, and capacity testing, lithium-ion battery A was obtained.

[0067] Example 2

[0068] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 0.5% of compound 1 to obtain the lithium-ion battery electrolyte of Example 2. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery B was obtained.

[0069] Example 3

[0070] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 3% of compound 1 to obtain the lithium-ion battery electrolyte of Example 3. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery C was obtained.

[0071] Example 4

[0072] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 1% of compound 3 to obtain the lithium-ion battery electrolyte of Example 4. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery D was obtained.

[0073] Example 5

[0074] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 1% of compound 7 to obtain the lithium-ion battery electrolyte of Example 5. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery E was obtained.

[0075] Example 6

[0076] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 1% of compound 8 to obtain the lithium-ion battery electrolyte of Example 6. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery F was obtained.

[0077] Example 7

[0078] Preparation of electrolyte: Unlike Example 1, 1% of compound 1 was replaced with 1% of compound 9 to obtain the lithium-ion battery electrolyte of Example 7. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery G was obtained.

[0079] Example 8

[0080] Preparation of electrolyte: Unlike Example 1, 1% lithium bisfluorosulfonylimide (1% LiFSI) was replaced with 0.5% lithium bisfluorosulfonylimide (0.5% LiFSI) to obtain the lithium-ion battery electrolyte of Example 8. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery H was obtained.

[0081] Example 9

[0082] Preparation of electrolyte: Unlike Example 1, 1% vinylene carbonate (1% VC) was replaced with 2% vinylene carbonate (2% VC) to obtain the lithium-ion battery electrolyte of Example 7. The prepared electrolyte was injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery I was obtained.

[0083] Comparative Example 1

[0084] Electrolyte preparation: The electrolyte was prepared in a dry room (environmental dew point below -40℃). Ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and ethylene carbonate (EC) were mixed in a volume ratio of 5:2:3 as an organic solvent, totaling 100 mL. Lithium hexafluorophosphate was added to this solvent to achieve a molar concentration of 1.1 mol / L. Then, 1% (by mass) of lithium bis(fluorosulfonyl)imide (1% LiFSI) and 1% (by mass) of ethylene carbonate (1% VC) were added, and the mixture was stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 1. The prepared electrolyte was injected into a pouch cell, and after standing, formation, and capacity testing, lithium-ion battery J was obtained.

[0085] Comparative Example 2

[0086] Electrolyte preparation: Unlike Comparative Example 1, 1% lithium bisfluorosulfonylimide (1% LiFSI) was replaced with 0.5% lithium bisfluorosulfonylimide (0.5% LiFSI) to obtain the lithium-ion battery electrolyte of Comparative Example 2. The prepared electrolyte was injected into a pouch cell, and after standing, formation and capacity testing, lithium-ion battery K was obtained.

[0087] Comparative Example 3

[0088] Electrolyte preparation: Unlike Comparative Example 1, 1% vinylene carbonate (1% VC) was replaced with 2% vinylene carbonate (2% VC) to obtain the lithium-ion battery electrolyte of Comparative Example 3. The prepared electrolyte was injected into a pouch cell, and after standing, formation and capacity testing, lithium-ion battery L was obtained.

[0089] Comparative Example 4

[0090] Preparation of electrolyte: Unlike Comparative Example 1, 1% ethylene sulfate (structural formula shown below) is added and stirred until completely dissolved to obtain the lithium-ion battery electrolyte of Comparative Example 4. The prepared electrolyte is injected into a soft-pack battery, and after standing, formation and capacity testing, lithium-ion battery M is obtained.

[0091]

[0092] The lithium-ion battery cathode material used in this experiment is LiNi. 0.5 Co 0.2 Mn 0.3 O2 (the positive electrode material is lithium nickel cobalt manganese oxide, where 0.5 ≤ molar fraction of nickel < 1), and the negative electrode is artificial graphite. The following experiments were conducted on the batteries obtained from Comparative Examples 1 to 4 and all Examples 1 to 9, and the test results are shown in Table 2.

[0093] 1. Low-temperature cycle performance test: The batteries obtained in Examples 1-9 and Comparative Examples 1-4 were charged at -20℃ with a constant current and constant voltage of 0.5C to a voltage of 4.4V and a cutoff current of 0.05C. After resting for 10 minutes, they were discharged at a constant current of 0.5C to 2.75V. This constituted one charge-discharge cycle. The obtained batteries were then subjected to 100 charge-discharge cycles at -20℃.

[0094] 2. High-Temperature Cycling Performance Test: The batteries obtained in Examples 1-9 and Comparative Examples 1-4 were charged at 45°C with a constant current and constant voltage of 1C to a voltage of 4.4V and a cutoff current of 0.05C. After resting for 10 minutes, they were discharged at a constant current of 1C to 2.75V. This constituted one charge-discharge cycle. The obtained batteries were then subjected to 500 charge-discharge cycles at 45°C.

[0095] The electrolyte formulations for Examples 1-9 and Comparative Examples 1-4 are shown in Table 1 below:

[0096] Table 1

[0097]

[0098] Table 2

[0099]

[0100] Referring to Table 2, comparing Examples 1-9 with Comparative Example 1, it can be seen that the compound with the structure shown in Formula I of the present invention, when combined with other additives, can effectively improve the battery capacity retention rate during low-temperature cycling and also improve the battery's high-temperature cycling performance. Comparing Examples 1-9 with Comparative Examples 1-3, it can be seen that simply mixing other additives (without adding the compound described in Formula I of the present invention) results in performance far inferior to the electrolyte formulation claimed in the present invention. Comparing Examples 1-9 with Comparative Example 4, it can be seen that the compound with the structure shown in Formula I of the present invention has superior performance compared to common sulfide compounds.

[0101] Table 3 shows the storage performance test results of the examples and comparative examples using the compound with the structure shown in Formula I of the present invention as an additive. The examples and comparative examples both showed good storage performance, while the examples showed better cycle performance. Therefore, it can be determined that the novel additive applied to the electrolyte results in superior overall battery performance.

[0102] Table 3

[0103]

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A nonaqueous electrolyte, characterized by comprising: The non-aqueous electrolyte comprises a non-aqueous organic solvent, a lithium salt, and a functional additive, the functional additive comprises a bis-sulfinic ester structure represented by Formula I, ； M is selected from unsubstituted arylene, unsubstituted heteroarylene; The functional additive further comprises other additives, the other additives are selected from a combination of one or more of lithium bisfluorosulfonimide, lithium fluorosulfonate, vinylene carbonate, fluoroethylene carbonate, lithium tetrafluoroborate.

2. The nonaqueous electrolyte according to claim 1, characterized by M is selected from phenyl, furan, thiophene, pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, pyrimidine.

3. The nonaqueous electrolyte according to any one of claims 1 to 2, characterized by The bis-sulfinic ester structure represented by Formula I is selected from any one or more of the following structures: ； ； ； ； ； ； 。 4. The nonaqueous electrolyte according to claim 1, characterized by Further comprising any one or more of the following conditions: A1) The mass fraction of the bis-sulfinic ester structure represented by Formula I in the non-aqueous electrolyte is 0.5% to 4%; A2) The lithium salt is selected from a combination of one or more of lithium hexafluorophosphate, lithium bisfluorooxalate phosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium bisfluorooxalate borate, lithium aluminum chloride, lithium bisoxalate borate, lithium chloride, lithium bromide, lithium iodide, lithium triflate, lithium bis(trifluoromethylsulfonyl)imide; A3) The concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L; A4) The non-aqueous organic solvent is selected from cyclic carbonate and / or chain carbonate; A5) The mass fraction of the non-aqueous organic solvent in the non-aqueous electrolyte is 71% to 91%.

5. The nonaqueous electrolyte according to claim 4, wherein Further comprising any one or more of the following conditions: A11) In feature A1), the mass fraction of the bis-sulfinic ester structure represented by Formula I in the non-aqueous electrolyte is 0.5% to 3%; A41) In feature A4), the non-aqueous organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, vinyl carbonate, propylene carbonate, gamma-butyrolactone, ethyl acetate, propyl acetate.

6. The nonaqueous electrolyte according to claim 1, wherein The mass fraction of the other additives in the non-aqueous electrolyte is 1.5% to 5%.

7. A lithium-ion battery, characterized by The battery module comprises a positive electrode, a negative electrode, a separator film arranged between the positive electrode and the negative electrode, and a non-aqueous electrolyte, characterized in that the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 6.

8. The lithium-ion battery of claim 7, wherein, Further comprising any one or more of the following conditions: B1) The negative electrode comprises a negative electrode active material, the negative electrode active material is selected from a combination of one or more of silicon-carbon, silicon-carbon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal; B2) The positive electrode comprises a positive electrode active material, the positive electrode active material is selected from a combination of one or more of lithium cobaltate, lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminum phosphate, lithium iron phosphate, and lithium iron manganese phosphate.

9. A battery module, characterized by The lithium ion battery according to claim 7 or 8.

10. A battery pack, characterized by, The battery module according to claim 9.

11. An electrical device, characterized by The lithium ion battery according to claim 7 or 8 is used as a power supply for the device, and the device includes a mobile device, an electric vehicle, an electric tool, an electric train, a satellite, a ship, and an energy storage system.

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