Non-aqueous electrolyte, lithium ion battery, battery module, battery pack and electric device

Abstract

The invention provides a non-aqueous electrolyte, a lithium ion battery, a battery module, a battery pack and an electric device. The non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and a functional additive, and the functional additive comprises a bis-sulfinyl ester structure as shown in a formula I in the specification. When the non-aqueous electrolyte is used in the lithium ion battery, the wettability of the electrolyte can be effectively enhanced, the ionic conductivity of the electrolyte is improved, the low-temperature discharge capacity of the electrolyte is improved, and the stability of the electrolyte under high-temperature and high-voltage conditions is improved; and thus, the discharge capability and the service life of the lithium ion battery in high-temperature storage and high-temperature circulation are improved.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and in particular to a non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device. Background Technology

[0002] With the rapid development of China's new energy industry, the demand for power batteries and energy storage batteries has further increased, leading to a growing need for high-energy-density, long-cycle, wide-temperature-range, high-power-density, and environmentally friendly lithium-ion batteries. Therefore, optimizing one or more of these aspects and designing more suitable electrolyte formulations and novel electrolyte additives are crucial for further improving the overall performance of batteries.

[0003] Batteries typically operate within a temperature range of 0-40 degrees Celsius. When batteries are in low ambient temperatures, the viscosity of the electrolyte increases, inhibiting the conductivity of ions and increasing the internal impedance of the battery, thus affecting its discharge capacity. Therefore, improving the low-temperature discharge capability of batteries has become an important topic of discussion. Consequently, developing and designing a lithium-ion battery with a wider temperature range is particularly crucial.

[0004] Based on this, the present invention designs a novel electrolyte additive and a reasonable ratio of lithium salt, solvent and additive to create a non-aqueous electrolyte for lithium-ion batteries with optimized low-temperature performance, enabling lithium-ion batteries to have excellent low-temperature discharge performance and cycle performance. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. When the non-aqueous electrolyte of this invention is used in a lithium-ion battery, it can effectively enhance the wettability of the electrolyte, improve the ionic conductivity of the electrolyte, enhance the low-temperature discharge capability of the electrolyte, and improve the stability of the electrolyte under high temperature and high voltage conditions, thereby improving the discharge capability and service life of the lithium-ion battery under high temperature storage and high temperature cycling.

[0006] To achieve the above and other related objectives, a first aspect of the present invention provides a non-aqueous electrolyte comprising a lithium salt, a non-aqueous organic solvent, and a functional additive, wherein the functional additive comprises a bis(sulfinyl) ester structure represented by Formula I. ; Wherein, M is selected from substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0007] A second aspect of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte of the first aspect of the present invention.

[0008] A third aspect of the present invention provides a battery module comprising the lithium-ion battery described in the second aspect of the present invention.

[0009] A fourth aspect of the present invention provides a battery pack including the battery module described in the third aspect of the present invention.

[0010] A fifth aspect of the present invention provides an electrical device comprising the lithium-ion battery described in the second aspect of the present invention, wherein the lithium-ion battery serves as a power source for the electrical device, and the electrical device includes mobile devices, electric vehicles, power tools, electric trains, satellites, ships, and energy storage systems.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention uses a compound with the structure shown in Formula I as an electrolyte additive. This compound has good wettability, which increases the interaction between the electrolyte and the electrode, enabling more efficient ion transport at lower temperatures. Better wettability also positively affects the desolvation process of lithium ions intercalating from the electrolyte into the electrode, thus inhibiting the formation of dead lithium. Its inherent symmetry also positively affects lithium salt dissolution and interaction with other organic solvents.

[0012] (2) The present invention uses a compound with the structure shown in Formula I, which has a thionyl functional group, giving it a high reduction potential. This allows it to preferentially form a thin and stable electrolyte interface (SEI film) at the negative electrode, which is faster than the solvent. The sulfur-containing SEI film has a positive effect on improving the thermal and chemical stability of the interface. When used in combination with other additives, it can regulate the reduction potential of other additives, inhibit the film-forming reaction of other additives, and protect other additives, thereby improving the overall stability of the battery and increasing the cycle performance and service life of the battery. Detailed Implementation

[0013] The following details the implementation methods of the non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device provided by the present invention.

[0014] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, 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 expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0015] [Non-aqueous electrolyte] A first aspect of the present invention provides a non-aqueous electrolyte comprising a non-aqueous organic solvent, a lithium salt, and a functional additive, wherein the functional additive comprises a bis(sulfinyl) ester structure as shown in Formula I.

[0016] Wherein, M is selected from substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted hypounsaturated hydrocarbon, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0017] In some embodiments, M is selected from substituted or unsubstituted alkylene groups, and may be substituted or unsubstituted C1-C30 alkylene groups, substituted or unsubstituted C1-C20 alkylene groups, substituted or unsubstituted C1-C10 alkylene groups, substituted or unsubstituted C1-C8 alkylene groups, substituted or unsubstituted C1-C6 alkylene groups, or substituted or unsubstituted C1-C4 alkylene groups. Alkylene groups include, but are not limited to, methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, tert-butylene, and sec-butylene. Substituents include, for example, deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0018] In some embodiments, M is selected from substituted or unsubstituted cycloalkylene groups. Options include substituted or unsubstituted C3-C30 cycloalkylene groups, substituted or unsubstituted C3-C20 cycloalkylene groups, substituted or unsubstituted C3-C10 cycloalkylene groups, substituted or unsubstituted C3-C8 cycloalkylene groups, substituted or unsubstituted C3-C6 cycloalkylene groups, and substituted or unsubstituted C3-C4 cycloalkylene groups. Examples of cycloalkylene groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, and cyclohexenyl. Substituents include deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0019] In some embodiments, M is selected from substituted or unsubstituted hypounsaturated hydrocarbon groups. Options include substituted or unsubstituted C2-C30 hypounsaturated hydrocarbon groups, substituted or unsubstituted C2-C20 hypounsaturated hydrocarbon groups, substituted or unsubstituted C2-C10 hypounsaturated hydrocarbon groups, substituted or unsubstituted C2-C8 hypounsaturated hydrocarbon groups, substituted or unsubstituted C2-C6 hypounsaturated hydrocarbon groups, substituted or unsubstituted C2-C4 hypounsaturated hydrocarbon groups, etc. Hypounsaturated hydrocarbon groups include, but are not limited to, vinylene, ethynylene, isopropynyl, isopropynyl, isobutylene, isopentenyl, 1,4-dibutenyl, etc. The substituents may be selected, for example, from deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0020] In some embodiments, M is selected from substituted or unsubstituted heterocyclic groups. Options include substituted or unsubstituted aziridine butyl, substituted or unsubstituted aziridine pentyl, substituted or unsubstituted aziridine hexyl, substituted or unsubstituted oxohexyl, substituted or unsubstituted pyridinealkyl, substituted or unsubstituted imidazoalkyl, substituted or unsubstituted pyridinealkyl, etc. The substituent may be selected from deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0021] In some embodiments, M is selected from substituted or unsubstituted aryl groups, and may be selected from substituted or unsubstituted C6-C60 aryl groups, substituted or unsubstituted C6-C50 aryl groups, substituted or unsubstituted C6-C40 aryl groups, substituted or unsubstituted C6-C30 aryl groups, substituted or unsubstituted C6-C30 aryl groups, substituted or unsubstituted C6-C15 aryl groups, and substituted or unsubstituted C6-C12 aryl groups. The substituent may be selected from deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0022] In some embodiments, M is selected from substituted or unsubstituted heteroaryl groups, and may be substituted or unsubstituted C6-C60 heteroaryl groups, substituted or unsubstituted C6-C50 heteroaryl groups, substituted or unsubstituted C6-C40 heteroaryl groups, substituted or unsubstituted C6-C30 heteroaryl groups, substituted or unsubstituted C6-C30 heteroaryl groups, substituted or unsubstituted C6-C15 heteroaryl groups, substituted or unsubstituted C6-C12 heteroaryl groups. The substituent may be selected from deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, imide, oxo, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0023] In some specific embodiments, M is selected from substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups.

[0024] In some specific embodiments, M is selected from unsubstituted aryl or unsubstituted heteroaryl.

[0025] In some preferred embodiments, M is selected from phenyl, furan, thiophene, pyrrole, pyrazole, oxazole, thiazole, imidazole, pyridine, and pyrimidine.

[0026] In some specific embodiments of the present invention, the bissulfinate structure represented by Formula I is selected from any one or more of the following structures: ; ; ; ; ; ; .

[0027] This invention employs a compound with the structure shown in Formula I as an electrolyte additive. This compound possesses excellent wettability, enhancing the interaction between the electrolyte and the electrode, enabling more efficient ion transport at lower temperatures. The improved wettability also positively impacts the desolvation process during lithium ion insertion from the electrolyte into the electrode, thus inhibiting the formation of dead lithium. Furthermore, its inherent symmetry positively influences lithium salt dissolution and interactions with other organic solvents.

[0028] In the non-aqueous electrolyte provided by this invention, the bis(sulfinyl) ester structure represented by Formula I accounts for 0.5% to 4% of the total mass. In some embodiments, the mass percentage of the bis(sulfinyl) ester structure represented by Formula I in the non-aqueous electrolyte can be, for example, 0.5% to 1%, 1% to 3%, 3% to 4%, 0.5% to 3%, 0.5% to 2%, 2% to 4%, etc. Optionally, the mass percentage of the bis(sulfinyl) ester structure represented by Formula I in the non-aqueous electrolyte is 0.5% to 3%. Within the above range, the advantage is that the additive can exert its maximum effect. Outside the range, the disadvantage is that a low content results in insufficient effect, while a high content leads to increased battery impedance, thereby affecting battery performance.

[0029] The non-aqueous electrolyte provided by this invention further includes other additives, which are selected from one or more combinations of fluoroethylene carbonate, difluoroethylene carbonate, tris(trimethylsilane) phosphate, tris(trimethylsilane) borate, lithium difluorosulfonylimide, tetravinylsilane, lithium trifluoromethanesulfonate, lithium fluorosulfonate, lithium aminosulfonate, lithium tetrafluoroborate, methanedisulfonate, N-methyldi(fluorosulfonyl)imide, vinylene carbonate, vinyl sulfate, dimethyl sulfate, 4,5-dicyano-2-methylimidazole, and 4,5-dicyano-2-ethylimidazole. Preferably, the other additives are selected from one or more combinations of lithium difluorosulfonylimide, lithium fluorosulfonate, vinylene carbonate, fluoroethylene carbonate, and lithium tetrafluoroborate; more preferably, the other additives are selected from a combination of lithium difluorosulfonylimide and vinylene carbonate. This invention utilizes a compound with the structure shown in Formula I, which has a thionyl functional group, giving it a high reduction potential. This allows it to preferentially form a thin and stable electrolyte interface (SEI film) at the negative electrode, prioritizing the formation of a sulfur-containing SEI film. This process positively enhances the thermal and chemical stability of the interface. When used in combination with other additives, it can regulate the reduction potential of these additives, inhibit their film-forming reactions, and protect them. Ultimately, this improves the overall stability of the battery, increasing its cycle performance and lifespan.

[0030] In the non-aqueous electrolyte provided by this invention, the other additives account for 1.5% to 5% of the total mass of the non-aqueous electrolyte. In some embodiments, the other additives may account for 1.5% to 2%, 2% to 3%, 3% to 5%, 2% to 4%, or 4% to 5% of the total mass of the non-aqueous electrolyte. In some embodiments, the other additives account for 1.5% to 3% of the total mass of the non-aqueous electrolyte. Within the above range, the advantage is that the synergistic effect of the additives can be maximized, improving battery performance. Outside the range, the disadvantage is that it may affect the stability of the SEI film of the battery, degrading battery performance.

[0031] In the non-aqueous electrolyte provided by this invention, the lithium salt is selected from one or more combinations of lithium hexafluorophosphate, lithium difluorooxalate phosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium difluorooxalate borate, lithium aluminum chloride, lithium dioxalate borate, lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonic acid)imide.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Lithium-ion batteries 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.

[0036] 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.

[0037] 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.

[0038] 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).

[0039] 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.

[0040] 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.

[0041] Battery Module 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.

[0042] Battery Pack 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.

[0043] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0044] Electrical appliances 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.

[0045] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] Example 1 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.

[0050] Example 2 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.

[0051] Example 3 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.

[0052] Example 4 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.

[0053] Example 5 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.

[0054] Example 6 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.

[0055] Example 7 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.

[0056] Example 8 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.

[0057] Example 9 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.

[0058] Comparative Example 1 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.

[0059] Comparative Example 2 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.

[0060] Comparative Example 3 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.

[0061] Comparative Example 4 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.

[0062] 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.

[0063] 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℃.

[0064] 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.

[0065] The electrolyte formulations for Examples 1-9 and Comparative Examples 1-4 are shown in Table 1 below: Table 1

[0066] Table 2

[0067] 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.

[0068] 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.

[0069] Table 3

[0070] 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, wherein the functional additive comprises a bis(sulfinyl) ester structure as shown in Formula I. ； Wherein, M is selected from substituted or unsubstituted alkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted hypounsaturated hydrocarbon, substituted or unsubstituted heterocyclic, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

2. The nonaqueous electrolyte according to claim 1, characterized by M is selected from substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups.

3. The nonaqueous electrolyte according to claim 1, wherein M is selected from unsubstituted aryl or unsubstituted heteroaryl.

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

5. The non-aqueous electrolyte according to any one of claims 1 to 4, characterized in that, The bissulfinate structure represented by Formula I is selected from one or more of the following structures: ； ； ； ； ； ； 。 6. The non-aqueous electrolyte according to claim 1, characterized in that, It also includes one or more of the following conditions: A1) The functional additives also include other additives selected from one or more combinations of fluoroethylene carbonate, difluoroethylene carbonate, tris(trimethylsilane) phosphate, tris(trimethylsilane) borate, lithium difluorosulfonylimide, tetravinylsilane, lithium trifluoromethylsulfonate, lithium fluorosulfonate, lithium aminosulfonate, lithium tetrafluoroborate, methanedisulfonate, N-methyldi(fluorosulfonyl)imide, vinylene carbonate, vinyl sulfate, dimethyl sulfate, 4,5-dicyano-2-methylimidazole, and 4,5-dicyano-2-ethylimidazole; A2) The bis(sulfinyl) ester structure shown in Formula I accounts for 0.5% to 4% of the mass of the non-aqueous electrolyte; A3) The lithium salt is selected from one or more combinations of lithium hexafluorophosphate, lithium difluorooxalate phosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium difluorooxalate borate, lithium aluminum chloride, lithium difluorooxalate borate, lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonate)imide. A4) The concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L; A5) The non-aqueous organic solvent is selected from cyclic carbonates and / or chain carbonates; A6) The non-aqueous organic solvent accounts for 71% to 91% of the mass of the non-aqueous electrolyte.

7. The non-aqueous electrolyte according to claim 6, characterized in that, It also includes one or more of the following conditions: A11) In feature A1), the other additives are selected from one or more combinations of lithium bis(fluorosulfonyl)imide, lithium fluorosulfonate, vinylene carbonate, fluoroethylene carbonate, and lithium tetrafluoroborate. A12) In feature A1), the other additives account for 1.5% to 5% of the mass of the non-aqueous electrolyte; A21) In feature A2), the bis(sulfinyl) ester structure represented by formula I accounts for 0.5% to 3% of the mass of the non-aqueous electrolyte; A51) In feature A5), 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.

8. A lithium-ion battery, characterized in that, The invention comprises a positive electrode, a negative electrode, a separator membrane spaced between the positive and negative electrodes, 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 7.

9. The lithium-ion battery according to claim 8, characterized in that, It also includes one or more of the following conditions: B1) The negative electrode includes a negative electrode active material, which is selected from one or more combinations of silicon carbon, silicon carbon oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon and lithium metal; B2) The positive electrode includes a positive electrode active material, which is 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.

10. A battery module, characterized in that, Including the lithium-ion battery according to claim 8 or 9.

11. A battery pack, characterized in that, Includes the battery module according to claim 10.

12. An electrical appliance, characterized in that, Includes the lithium-ion battery according to claim 8 or 9, wherein the lithium-ion battery is used as a power source for the device, and the device includes mobile devices, electric vehicles, power tools, electric trains, satellites, ships, and energy storage systems.

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