Electrolyte, battery, and battery module

Abstract

The present application provides an electrolyte, a battery, and a battery module, relating to the field of battery technology. The electrolyte comprises an electrolyte salt, an organic solvent, and an additive, characterized in that the additive comprises a sulfonate-containing compound represented by Formula 1. The electrolyte provided by the present application can achieve better performance optimization with fewer types of additives.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrolyte, a battery, and a battery module. Background Art

[0002] As one of the main components of lithium-ion, sodium-ion, and potassium-ion batteries, electrolytes play a crucial role in transporting active ions. However, regardless of the system, electrolytes constantly undergo side reactions with the positive and negative electrodes and at the interface, leading to their continuous consumption. This repetitive cycle not only leads to gassing but also significantly degrades cycling performance. Temperature significantly affects both the electrolyte's own properties and those related to its electrode interface. When the temperature exceeds the electrolyte's normal operating range, the electrolyte undergoes irreversible chemical reactions (such as high-temperature oxidative decomposition), causing rapid battery performance failure and even safety accidents. Electrolyte additive engineering plays a crucial role in current systems. However, single additives typically address specific issues (such as VC film formation, LiTFSI conductivity enhancement, and LiBOB cathode stabilization). Each additive typically contains only a single functional group. To address the diverse requirements of the positive and negative electrode / electrolyte interface, existing technologies typically employ a combination of multiple additives. However, with increasing demands for gassing expansion, thermal stability, cycling performance, and capacity, the increasing number of additives in battery electrolytes can lead to compatibility issues, increased side reactions, and increased costs. For example, CN116826175A discloses a wide-temperature non-aqueous electrolyte, which not only uses sulfonate compounds as additives but also adds a variety of additives such as fluoro-1,3-propane sultone, difluoroethylene carbonate, and lithium difluorooxalatoborate. Although this electrolyte can improve the high-temperature cycle performance of the battery, the improvement effect is difficult to meet the required requirements. Summary of the Invention

[0003] The purpose of the present application is to provide an electrolyte that uses a compound of a specific structure as one of its additives, which can improve the battery's normal and high-temperature cycle performance and resistance to strong volume change with fewer types of additives.

[0004] One of the objectives of this application is to provide a battery.

[0005] Another object of the present application is to provide a battery module.

[0006] One of the purposes of this application is to provide an electrical device.

[0007] In a first aspect, in order to solve the above-mentioned problem, the present application provides an electrolyte solution, comprising an electrolyte salt, an organic solvent, and an additive, wherein the additive comprises a sulfonate-containing compound represented by Formula 1;

[0008]

[0009] Formula 1

[0010] in, represents a C3-C8 cycloalkane or cycloalkene, R1 represents a hydrogen atom or a C1-C4 alkyl or alkenyl or fluoroalkyl or fluoroalkenyl, R2 represents a benzene ring or a fluoro, cyano-substituted, methyl-substituted benzene ring, a sulfonate-substituted benzene ring, a cyclic ether-substituted benzene ring, a cyclic carbonyl-substituted benzene ring, or a C1-C6 alkyl or fluoroalkyl or a C2-C6 alkenyl or fluoroalkenyl, and n is 0 or 1;

[0011] and, and at least one of R1 includes an alkenyl group or fluorine.

[0012] Furthermore, in some embodiments of the present application, the structural formula of the sulfonate-containing compound represented by Formula I is any one selected from the following structures:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] .

[0019] Furthermore, in some embodiments of the present application, the additive includes a first additive and a second additive;

[0020] The first additive is a non-sulfonate additive, and the first additive is a non-sulfone additive;

[0021] The second additive is a sulfonate additive, and the second additive is any one of the sulfonate-containing compounds shown in Formula I.

[0022] Furthermore, in some embodiments of the present application, the first additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, phthaleinsulfonamide, and vinyl sulfate.

[0023] Furthermore, in some embodiments of the present application, the types of additives in the electrolyte are no more than 3.

[0024] Furthermore, in some embodiments of the present application, the amount of the second additive added to the electrolyte is 0.1-2% by mass.

[0025] Furthermore, in some embodiments of the present application, the amount of the second additive added to the electrolyte is 0.2-1% by mass.

[0026] Furthermore, in some embodiments of the present application, the electrolyte salt is one or more of XPF6, XClO4, XBF4, XAsF6, XFSI, XTFSI, XBOB, XODFB, XCF3SO3, XPO2F2 or XOTFB; wherein X includes any one of Li, Na or K.

[0027] Furthermore, in some embodiments of the present application, the organic solvent includes any one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), 2,2-difluoroethyl acetate (DFEA), acetonitrile (AN), ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or tetrahydrofuran, or a combination of at least two thereof.

[0028] Furthermore, in some embodiments of the present application, the concentration of the electrolyte salt in the battery electrolyte is 0.8-1.2 mol / L.

[0029] Furthermore, in some embodiments of the present application, based on the mass of the electrolyte being 100%, the content of the organic solvent is 58.5% to 92.7%.

[0030] Furthermore, in some embodiments of the present application, the amount of the first additive added to the electrolyte is 1-8% by mass.

[0031] In a second aspect, the present application further provides a battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and the electrolyte as described in the first aspect.

[0032] Furthermore, in some embodiments of the present application, the battery is a lithium ion battery, a sodium ion battery, a potassium ion battery or a supercapacitor.

[0033] Furthermore, in some embodiments of the present application, the negative electrode includes a negative electrode active material, and the negative electrode active material is selected from one or a combination of at least two of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microbeads, graphene, graphyne, metallic lithium / sodium / potassium, nanocarbon, carbon nanotubes, elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon / copper oxide composites, AG composites, silicon alloys, elemental tin, tin oxide compounds, tin-carbon composites, tin alloys or lithium titanate.

[0034] Furthermore, in some embodiments of the present application, the positive electrode includes a positive electrode active material, and the positive electrode active material is selected from one or a combination of at least two of NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LRMO (lithium-rich manganese), LCO (lithium cobalt oxide), LFP (lithium iron phosphate), LMFP (lithium iron manganese phosphate), NaxMO2 (layered oxide), NFS (sodium ferric fluorosulfate), and NFPP (sodium iron pyrophosphate).

[0035] Furthermore, in some embodiments of the present application, the diaphragm is selected from any one of a polyolefin diaphragm and a composite ceramic membrane.

[0036] In a third aspect, the present application further provides a battery module, comprising the battery described in the first aspect or the electrolyte described in the second aspect.

[0037] In a fourth aspect, the present application further provides an electrical device, comprising the electrolyte described in the first aspect, the battery described in the second aspect, or the battery module described in the third aspect.

[0038] The present application provides an electrolyte, wherein a sulfonate additive of a specific structure is used in the electrolyte. The molecular structure of the additive includes, in addition to the sulfonate group, at least a C3-C6 cyclic hydrocarbon functional group connected to the ester group and containing an alkenyl or fluorine, and a functional group connected to the sulfonic acid group and containing an unsaturated group or an alkyl group and showing electrode interface modification, so that the additive has multiple functions that are beneficial to improving / improving the performance / defects of the secondary battery such as low cycle capacity retention rate, rapid interface impedance growth, and poor high-temperature storage performance. It can not only The realization of compounding multiple additives in the same molecule, such as the compounding of conventional sulfonic acid ester additives with unsaturated bond-containing additives (such as PST (1,3-propenyl-sultone), TVSI (tetravinylsilane)), nitrile-containing additives (such as ADN (adiponitrile), HTCN (1,3,6-hexanetricarbonitrile)), and fluorobenzene additives, aims to solve technical problems such as severe side reactions within the battery cell at high temperatures, positive electrode protection, and inhibition of metal ion dissolution and electrode wetting. It can also improve compatibility and side reaction problems caused by compounding multiple additives. In addition, the applicant has also found that the additive with a specific structure provided by this application can not only exert the specific technical effects of multiple functional groups, but also, due to their synergistic effect, it can even perform better in optimizing battery performance.

[0039] The lithium secondary battery formed based on the electrolyte provided in the present application has a residual capacity retention rate of more than 90% after storage at 60°C for 60 days, a capacity recovery retention rate of more than 91% after storage at 60°C for 60 days, a DCR growth rate of no more than 50% after storage at 60°C for 60 days, a capacity retention rate of 89.1% after 350 cycles of normal temperature cycling, and a capacity retention rate of 85.0% after 300 cycles of 45°C high temperature cycling. It can be seen that the electrolyte provided in the present application significantly improves the normal and high temperature cycling and high temperature stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figures 1 to 4 This is a mass spectrometry detection diagram of the compounds provided in some examples of the present application. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions of this application in conjunction with the embodiments. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] In the description of this application, it should be understood that the terms "first," "second," and "first" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, features defined as "first," "second," and "first" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0044] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0045] The electrolytes in non-aqueous electrolyte secondary batteries typically incorporate additives based on the desired technical issues. However, in existing technologies, the functions of each additive are relatively limited. For example, ethylene carbonate and 1,3-propene sultone (1,3-PS) can improve battery cycle performance, while isocyanate additives can improve cycle life. Some additives containing cyano groups can improve battery electrical performance, and some additives containing sultone groups can improve battery cycle life. Therefore, to achieve improvements in battery cycle performance, cycle life, and electrical properties, existing technologies typically employ a combination of multiple additives. However, with increasingly demanding battery application requirements, for example, to enhance high-temperature stability and high-voltage resistance, additional additives are needed to achieve the desired effects. Consequently, the number of additives in existing electrolytes is increasing, placing greater demands on the coordination of the various additives. Furthermore, the addition of too many additives can lead to side reactions, making it difficult for each additive to fully enhance battery performance. Based on this technical problem, the applicant creatively proposed a new electrolyte. In this electrolyte, by designing the molecular structure of its additives, it combines the technical effects of multiple additives, reducing the number of additives required to achieve the same effect. At the same time, it can avoid the defects of incompatibility between additives and possible side reactions caused by too many types of additives, thereby achieving the purpose of simplifying the electrolyte formula and improving battery performance. Based on this specific electrolyte additive provided by this application, the applicant also unexpectedly discovered that the battery based on this electrolyte has significantly improved high-temperature stability compared to the battery with an electrolyte formed by a combination of multiple additives.

[0046] The electrolyte of the present application includes electrolyte salt, organic solvent, and additives.

[0047] [additive]

[0048] The electrolyte provided in the present application includes at least the following additives, the structural formula of which is shown in Formula I below:

[0049]

[0050] in, represents a C3-C8 cycloalkane or cycloalkene, R1 represents a hydrogen atom or a C1-C4 alkyl or alkenyl or fluoroalkyl or fluoroalkenyl, R2 represents a benzene ring or a fluoro, cyano-substituted, methyl-substituted benzene ring, a sulfonate-substituted benzene ring, a cyclic ether-substituted benzene ring, a cyclic carbonyl-substituted benzene ring, or a C1-C6 alkyl or fluoroalkyl or a C2-C6 alkenyl or fluoroalkenyl, n is 0 or 1; and, and at least one of R1 includes an alkenyl group or fluorine.

[0051] It should be noted that the additives provided in this application contain at least two functional groups that are beneficial to the battery, such as sulfonate groups, Or the alkenyl or fluorine substituent included in the functional group represented by R1. It should be noted that, in this application, Or the connection relationship between the alkenyl or fluorine substituent included in the functional group represented by R1 and the sulfonate group needs to satisfy the molecular structure shown in Formula I, and when When it is a cycloolefin, the double bond on the ring is not directly connected to the -O- in the sulfonate group. Or the alkenyl group, fluorine substituent group, and sulfonate group included in the functional group represented by R1 can all play a relatively good role in exerting their beneficial effects on the battery, making the technical effects achieved better.

[0052] It is possible that the compound represented by the general structural formula shown in Formula I can achieve a good synergistic effect of the functional groups in the molecule through its special electronic structure and polarity, so that the interface has a sulfur-rich membrane with high ionic conductivity, a polymer long-chain membrane that can adapt to large volume changes, and a lone pair of electrons and the positive transition metal (such as Co³⁺ / Ni 4+ ) forms a strong coordination bond to inhibit the dissolution of metal ions, and has the technical effect of improving the cycle capacity retention rate and high-temperature storage performance of the secondary battery based on the electrolyte. At the same time, within a certain range of addition amount, it can also play a role in inhibiting the growth of battery internal resistance.

[0053] Specifically, the compound represented by the general structural formula of Formula I may be a compound having the following structure:

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] .

[0060] In the present application, the compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I is added to the electrolyte as an additive. Preferably, only the compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I is added, and no more than three additives are added. Adding too many types of additives is not conducive to optimizing battery performance.

[0061] At the same time, when the compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I is added to the electrolyte as an additive, its addition amount should also be too high, because too high an addition amount is not conducive to optimizing battery performance. For example, the amount of the compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I added to the electrolyte is 0.1-2% by mass, preferably 0.2-1%, and more preferably 0.2-0.6%. For example, the amount of the compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I added to the electrolyte is preferably 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95% or 1.00, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges may be combined with any other ranges.

[0062] It should also be noted that when more than one compound represented by the above chemical formula or the compound represented by the general structural formula of Formula I is added to the electrolyte, the total amount added is preferably controlled within the above range, which is more conducive to optimizing battery performance.

[0063] In some embodiments of the present application, other functional additives may be added to the electrolyte, such as common vinylene carbonate (VC), fluoroethylene carbonate (FEC), phthaleinsulfathiazole (PST), and dithiothreitol disulfate (DTD). It should be noted that the other functional additives are preferably non-sulfonic acid additives and non-sulfone additives.

[0064] When other functional additives are added, the total amount of the other functional additives added to the electrolyte is 1-8% by mass, preferably 2-7.5%, and more preferably 3-6%. For example, the amount of the other functional additives added to the electrolyte is preferably 4.5, 5.2, 5.5, 6.3, 6.8, etc., and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0065] [Organic solvents]

[0066] The electrolyte provided in the present application also includes an organic solvent for dissolving electrolyte salts and additives, wherein the organic solvent can be selected from any one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), 2,2-difluoroethyl acetate (DFEA), acetonitrile (AN), ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or tetrahydrofuran, or a combination of at least two thereof.

[0067] Taking the mass of the electrolyte as 100%, the content of the organic solvent is 58.5% to 92.7%, preferably 69.4% to 88.2%. For example, the content of the organic solvent in the electrolyte is 58.5%, 59%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88% or 90% by mass, and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0068] [Electrolyte salt]

[0069] The electrolyte salt in this application is a key salt used for ion transport in secondary batteries. It dissolves in an organic solvent and provides mobile ions, such as lithium ions, sodium ions, and potassium ions, for battery charging and discharging. Depending on the ions transported by the battery, the electrolyte salt can be a lithium salt, a sodium salt, or a potassium salt. For example, the electrolyte salt used in the electrolyte provided in this application can be one or more of XPF6, XClO4, XBF4, XAsF6, XFSI, XTFSI, XBOB, XODFB, XCF3SO3, XPO2F2, or XOTFB; wherein X includes any one of Li, Na, or K. Taking the application of the electrolyte in a lithium-ion battery as an example, the electrolyte salt can be one or more of LiPF6, LiClO4, LiBF4, LiAsF6, LiFSI, LiTFSI, LiBOB, LiODFB, LiCF3SO3, LiPO2F2, or LiOTFB.

[0070] In the electrolyte solution of the present application, the concentration of the electrolyte salt may be 0.8-1.2 mol / L, preferably 0.9-1.1 mol / L. For example, the concentration of the electrolyte salt in the electrolyte can be 0.80 mol / L, 0.82 mol / L, 0.84 mol / L, 0.86 mol / L, 0.88 mol / L, 0.88 mol / L, 0.90 mol / L, 0.92 mol / L, 0.94 mol / L, 0.96 mol / L, 0.98 mol / L, 1.00 mol / L, 1.02 mol / L, 1.04 mol / L, 1.06 mol / L, 1.08 mol / L, 1.10 mol / L, 1.12 mol / L, 1.14 mol / L, 1.16 mol / L, 1.18 mol / L or 1.20 mol / L, and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0071] [Battery]

[0072] The present application also provides a battery based on the above electrolyte, the battery comprising a negative electrode, a positive electrode, a separator located between the negative electrode and the positive electrode to provide isolation and ion transport, and an electrolyte. The negative electrode material, positive electrode material, and separator material can be adapted to suit the battery type, such as a lithium battery, a sodium battery, or a potassium battery. The following takes a lithium-ion battery as an example:

[0073] The negative electrode may include a negative electrode active material selected from one or a combination of at least two of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microbeads, graphene, graphyne, metallic lithium / sodium / potassium, nanocarbon, carbon nanotubes, elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon / copper oxide composites, AG composites, silicon alloys, elemental tin, tin oxide compounds, tin-carbon composites, tin alloys, or lithium titanate. The negative electrode also includes a negative electrode current collector for conducting electrons; the negative electrode active material is disposed within the negative electrode current collector, which may be a metal or alloy material such as aluminum, nickel, tin, or copper. Furthermore, an adhesive layer may be provided between the negative electrode current collector and the negative electrode active material to adhere the negative electrode active material to the negative electrode current collector. The adhesive layer may be made of any adhesive material that can achieve the aforementioned purpose, and will not be described in detail in this application.

[0074] The positive electrode includes a positive electrode active material selected from one or a combination of at least two of the following: NCM (lithium nickel cobalt manganese oxide), NCA (lithium nickel cobalt aluminum oxide), LRMO (lithium-rich manganese oxide), LCO (lithium cobalt oxide), LFP, LMFP (lithium iron manganese phosphate), NaxMO2 (layered oxide), NFS (sodium ferrous fluorosulfate), and NFPP. The positive electrode also includes a positive electrode current collector for conducting electrons; the positive electrode active material is disposed within the positive electrode current collector, which may be a metal or alloy material such as aluminum, nickel, tin, or copper. Furthermore, an adhesive layer may be disposed between the positive electrode current collector and the positive electrode active material to adhere the positive electrode active material to the positive electrode current collector. The adhesive layer may be made of any adhesive material that can achieve the aforementioned purpose and will not be described in detail in this application.

[0075] The diaphragm is selected from any one of a polyolefin diaphragm and a composite ceramic membrane. The polyolefin diaphragm may be, for example, a polyethylene diaphragm, a polypropylene diaphragm, or a diaphragm containing a polyethylene or polypropylene base. The composite ceramic membrane may include a diaphragm substrate and a ceramic layer formed on at least one side of the diaphragm substrate. The diaphragm substrate may be a polyethylene diaphragm, a polypropylene diaphragm, or a diaphragm containing a polyethylene or polypropylene base. The ceramic layer may be a film layer formed of any ceramic material, such as an aluminum oxide layer, that improves the diaphragm's strength, voltage resistance, heat resistance, and other properties.

[0076] [Battery Module]

[0077] The battery module provided in the present application is a battery module formed by the batteries provided above in a certain order and structural array, and the battery cells or battery packs contained therein are not limited in this application.

[0078] [Electrical equipment]

[0079] The power-consuming device provided herein includes at least one of the aforementioned battery modules, which is used to provide power to the device. Examples of such power-consuming devices include mobile communication devices (e.g., mobile phones), computers (e.g., laptops, iPads, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric trucks, etc.), electric trains, ships, satellites, and energy storage systems.

[0080] In order to facilitate those skilled in the art to better understand the innovative features of the present application, the technical solutions of the present application are further described in detail below in conjunction with the embodiments. The embodiments of the present application described in detail below are exemplary and are only used to explain the present application, and should not be understood as limiting the present application.

[0081] The raw materials used in this application, such as ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and lithium hexafluorophosphate, were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; additives such as VC and FEC were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. or Shanghai Myrel Biochemical Technology Co., Ltd.; 3-cyanobenzenesulfonyl chloride, triethylamine, and dichloromethane were purchased from Beijing Inokai Technology Co., Ltd. 2-Propylene-1-sulfonyl was purchased from Shanghai Adamas Reagent Co., Ltd. All other reagents were commercially available, and the comparative example additives were sourced from Shengtai Chemical.

[0082] Compounds 1 to 15 used in the following examples were prepared by the following methods:

[0083] Compound 1: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 3-cyanobenzenesulfonyl chloride (cas: 56542-67-7) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 3-cyanobenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes. Gradually increase the temperature to obtain the final product.

[0084] Compound 2: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 4-cyano-3-methylbenzenesulfonyl chloride (cas: 942199-57-7) and dissolve it in 15 mL of anhydrous dichloromethane. Add the dichloromethane solution containing 4-cyano-3-methylbenzenesulfonyl chloride dropwise to the reaction vessel. Reaction was continued at 0°C for 30 minutes. The reaction temperature was gradually increased to obtain the final product.

[0085] Compound 3: Weigh 3-cyclohexene-1-methanol into a reaction vessel, then add triethylamine. Place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 3-cyano-4,5-difluorobenzenesulfonyl chloride (cas: 1807047-95-5) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 3-cyano-4,5-difluorobenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0086] Compound 4: Weigh 3-cyclohexene-1-methanol into a reaction vessel, then add triethylamine. Place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 3,4-dicyanobenzenesulfonyl chloride (cas: 170697-25-3) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 3,4-dicyanobenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0087] Compound 5: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 4-fluoro-3-cyanobenzenesulfonyl chloride (cas: 351003-23-1) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 4-fluoro-3-cyanobenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0088] Compound 6: Weigh (4-methylenecyclohexyl)methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 3-cyanobenzenesulfonyl chloride (cas: 56542-67-7) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 3-cyanobenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes. Gradually increase the temperature to obtain the final product.

[0089] Compound 7: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 4-methylsulfonylbenzenesulfonyl chloride (cas: 82964-91-8) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 4-methylsulfonylbenzenesulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0090] Compound 8: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction flask in an ice-water bath at 0°C for 10 minutes. Weigh 3,5-bis(methylsulfonyl)benzenesulfonyl chloride (cas: 849035-99-0) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 3,5-bis(methylsulfonyl)benzenesulfonyl chloride dropwise to the reaction flask. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0091] Compound 9: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 1,3-benzodioxy-5-sulfonyl chloride (cas: 115010-10-1) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 1,3-benzodioxy-5-sulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0092] Compound 10: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 4-sulfonyl chloride-indanone (cas: 255895-78-4) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing 4-sulfonyl chloride-indanone to the reaction vessel dropwise. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0093] Compound 11: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Triethylamine was then added and the reaction flask was placed in an ice-water bath at 0°C for 10 minutes. 2-Butene-3-methyl-1-sulfonyl chloride (cas: 1596068-27-7) was weighed and dissolved in 15 mL of anhydrous dichloromethane. The dichloromethane solution containing 2-butane-1-sulfonyl chloride was gradually added dropwise to the reaction flask. The reaction was carried out at 0°C for 30 minutes. The temperature was then gradually increased to obtain the final product.

[0094] Compound 12: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Add triethylamine and place the reaction flask in an ice-water bath at 0°C for 10 minutes. Weigh 2-propylene-1-sulfonyl chloride (cas: 14418-84-9) and dissolve it in 15 mL of anhydrous dichloromethane. Add the dichloromethane solution dropwise to the reaction flask. Reaction at 0°C for 30 minutes. Gradually increase the temperature to obtain the final product.

[0095] Compound 13: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Add triethylamine and place the reaction flask in an ice-water bath at 0°C for 10 minutes. Dissolve ethylsulfonyl chloride (CAS: 594-44-5) in 15 mL of anhydrous dichloromethane. Add the dichloromethane solution dropwise to the reaction flask. Reaction at 0°C for 30 minutes. Gradually increase the temperature to obtain the final product.

[0096] Compound 14: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh 2-methylprop-2-ene-1-sulfonyl chloride (cas: 14568-34-4) and dissolve it in 15 mL of anhydrous dichloromethane. Add the dichloromethane solution dropwise to the reaction vessel. Reaction at 0°C for 30 minutes. Gradually increase the temperature to obtain the final product.

[0097] Compound 15: Weigh 3-cyclohexene-1-methanol and add it to a reaction vessel. Then add triethylamine and place the reaction vessel in an ice-water bath at 0°C for 10 minutes. Weigh (2E)-2-butene-1-sulfonyl chloride (cas: 219952-29-1) and dissolve it in 15 mL of anhydrous dichloromethane. Gradually add the dichloromethane solution containing (2E)-2-butene-1-sulfonyl chloride dropwise to the reaction vessel. React at 0°C for 30 minutes, then gradually increase the temperature to obtain the final product.

[0098] Example 1

[0099] This embodiment provides an electrolyte. The components used to form the electrolyte are weighed according to the electrolyte composition and dosage shown in Table 1. The electrolyte is prepared in a glove box (the filling gas is nitrogen and the gaseous water is less than 10 ppm). The specific steps are as follows:

[0100] According to the formula shown in Table 1, non-aqueous solvents such as ethylene carbonate (EC), diethyl carbonate (EMC), and ethyl methyl carbonate (EMC) are evenly mixed in proportion. The sulfonate additive shown in Compound 1 is added to the evenly mixed solvent bag in sequence, and mixed until there is no lithium salt residue at the bottom and the electrolyte is clear and not turbid, thereby obtaining an electrolyte with normal chromaticity, which is then stored in a refrigerator at -10°C.

[0101] Examples 2 to 23 were performed under the same conditions as Example 1, except that the electrolyte formulation shown in Table 1 was used to obtain the electrolyte.

[0102] The chemical structures of the compounds prepared above were detected by mass spectrometry, and some of the detection results were as follows: Figures 1 to 4 shown.

[0103] Comparative Example 1 to Comparative Example 12

[0104] The electrolyte was prepared under the same conditions as in Example 1, except that the raw material compositions in the comparative example shown in Table 1 were used;

[0105] Among them, the structural formula of the other additives used in Comparative Example 5 is compound A shown below:

[0106]

[0107] Compound A

[0108] The structural formula of the other additive used in Comparative Example 6 is compound B shown below:

[0109]

[0110] Compound B

[0111] The structural formula of the other additive used in Comparative Example 7 is compound C shown below:

[0112]

[0113] Compound C

[0114] The structural formula of the other additive used in Comparative Example 8 is compound D as shown below:

[0115]

[0116] Compound D

[0117] The structural formula of the other additive used in Comparative Example 9 is compound E shown below:

[0118]

[0119] Compound E.

[0120] In order to verify the optimization effect of the electrolyte provided in this application on the battery, the applicant used the electrolytes obtained in Examples 1 to 23 and Comparative Examples 1 to 12 as electrolytes to prepare corresponding ion batteries, which were specifically prepared as follows:

[0121] (1) Preparation of positive electrode sheet: Dissolve polyvinylidene fluoride (PVDF) evenly in N-methylpyrrolidone (NMP), then add the conductive agent Super P, mix thoroughly, and then add the positive electrode active material LiNi 0.8 Co 0 .1 Mn 0 .1 O2 powder is gradually added (LiNi 0.8 Co 0 .1 Mn 0 .1 The mass ratio of O2 powder, PVDF and conductive agent Super P is 97.4:1.3:1.3 to obtain positive electrode slurry (the solid content of the positive electrode slurry is 63.1%). The positive electrode slurry is coated on the current collector, and then dried, rolled and slit to obtain positive electrode sheets that can be directly stacked.

[0122] (2) Preparation of negative electrode sheets: artificial graphite, conductive carbon, silicon oxide powder, sodium carboxymethyl cellulose, and styrene-butadiene rubber in a mass ratio of 80.9:2.9:13.2:1.2:1.8 were pre-mixed and stirred at a speed of 250 rpm for 140 min to obtain a negative electrode slurry. The negative electrode slurry was then transferred to deionized water for dispersion. After mixing evenly, the negative electrode slurry was sieved. Finally, the sieved negative electrode slurry was coated on the negative electrode current collector, and then dried, rolled, and slit to obtain a negative electrode sheet that can be laminated.

[0123] (3) Cell production: The positive and negative electrodes after stripping are stacked on a stacking machine. The separator is made of a three-layer material of PP / PE / PP to form a soft-pack cell.

[0124] (4) Liquid injection, formation and aging:

[0125] After the battery cells are dried at high temperature, the electrolytes of the examples and comparative examples are injected into the soft-pack battery cells. After the electrolyte injection, the lithium battery undergoes initial packaging, surface cleaning and other preliminary processes to complete the preliminary work, and is left at room temperature for one day. The formation is carried out using a step-by-step formation method. The first step is a formation current of 0.05C, and constant current charging is applied for 2 hours. The second step is a formation current of 0.1C, and constant current charging is applied until the voltage reaches 3.85V. After formation, it is aged at 50°C for one day, cooled to room temperature and finally sealed.

[0126] The soft pack battery prepared above was subjected to 25°C and 45°C cycle and storage performance tests; the specific test methods are as follows:

[0127] (1) Room temperature cycle performance test

[0128] At 25°C, the lithium-ion batteries obtained in the Examples and Comparative Examples were charged at a constant current and constant voltage of 1C to 4.25 V. After standing for 5 minutes, they were discharged at a constant current of 1C to 2.5 V. This constituted one charge / discharge cycle. The lithium-ion batteries were cycled 350 times at 25°C under these conditions. The DCR value (R1) after 350 cycles was recorded according to the test method in 4.2.4.

[0129] Capacity retention rate (%) of lithium-ion battery after 350 cycles = (discharge capacity at the 350th cycle / first discharge capacity) × 100%.

[0130] (2) 45℃ high temperature cycle performance test

[0131] At 45°C, the lithium-ion batteries obtained in the examples and comparative examples were charged at a constant current and constant voltage of 1C to 4.25 V. After standing for 5 minutes, they were discharged at a constant current of 1C to 2.5 V. The above constituted one charge / discharge cycle. The lithium-ion batteries were cycled 300 times at 45°C under the above conditions.

[0132] Capacity retention rate of lithium-ion battery after 300 cycles (%) = (discharge capacity at the 300th cycle / first discharge capacity) × 100%.

[0133] (3) 60℃ high temperature storage test

[0134] The lithium-ion batteries obtained in the examples and comparative examples were subjected to one charge-discharge cycle at room temperature at a charge / discharge rate of 1C / 1C. The batteries were then charged to 4.25V under 1C constant current and constant voltage conditions, and the discharge capacities Q0 and R0 were recorded. The fully charged batteries were placed in a 60°C environment for long-term storage for 56 days. After removal, the batteries were discharged at 1C at 25°C, and the discharge capacity Qa was recorded. The batteries were then charged / discharged at 1C / 1C at 25°C, and the 1C discharge capacity Qb was recorded. Following the test method in 4.2.4, the battery DCR value Rb after 60 days of storage was recorded. The high-temperature storage residual capacity retention rate and recovery capacity retention rate of the battery after 56 days of storage were calculated using the following formula:

[0135] Residual capacity retention rate = Qa / Q0×100%; capacity recovery retention rate = Qb / Q0×100%.

[0136] (4) DCR test

[0137] The lithium-ion batteries of the embodiment and comparative example were placed in a constant temperature box at 25°C for 5 minutes, charged to 4.25V at a constant current and constant voltage of 1C, left to stand for 30 minutes, discharged to 50% SOC at 1C, left to stand for 60 minutes and recording the corresponding voltage value U1; finally, discharged at 4C for 30 seconds (recording the corresponding voltage value U2), and the DCR value R and DCR growth rate were calculated according to the following formula:

[0138] R=(U1-U2) / (I4C); DCR Increase=(Rb-R0) / R0×100%.

[0139] The test results are shown in Table 2.

[0140] As can be seen from Table 2, the electrolyte based on the second additive of Formula I provided herein, even without the addition of other additives, that is, only with Compound 1 as the additive, can achieve a capacity retention rate of 86.1% after 300 cycles at a high temperature of 45°C, and its DC resistance can still be controlled within the range of 60.5mohm. The high-temperature storage performance (storage at 60°C for 60 days) can also achieve a capacity retention rate of not less than 89.2%, and the DCR growth rate can be controlled within 49.2%. In addition, after adding VC or FEC, which are common in the field, as additives, its 25°C and 45°C capacity retention rates are slightly improved. In particular, after adding FEC as an additive, its normal high temperature capacity retention rate increases significantly. However, as can be seen from Comparative Examples 10-12, when the number of additives is further increased, the normal high temperature capacity retention rate of the battery decreases significantly instead of increasing. This may be because the addition of too many additives is not conducive to optimizing battery performance.

[0141] In addition, Table 2 also shows that the sulfonate additive of Formula 1 provided in this application not only improves cycle capacity retention and high-temperature storage performance, but also does not increase the DC impedance of the battery within a suitable addition range. In particular, the optimization of high-temperature storage performance is extremely significant compared to additives with other structures. This may be due to the cyclic structure and unsaturated bonds in the sulfonate additive of Formula 1, which can preferentially undergo ring-opening polymerization on the positive and negative electrode surfaces, making the positive and negative electrode interfaces more elastic to adapt to systems with large negative electrode volume changes (such as silicon-containing negative electrodes and metal batteries), isolating the electrode interface from the electrolyte, and the film can exist for a long time under high temperature conditions, inhibiting the occurrence of side reactions and reducing the consumption of electrolyte and active lithium / sodium / potassium ions. The sulfonate groups contained in it can form active components of lithium / sodium / potassium alkylsulfonates at the negative electrode during the formation stage, and the technical effect of forming a sulfur-rich interface film with high ionic conductivity also acts on the battery without being affected.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0143] Table 1

[0144]

[0145] Table 2

[0146]

Claims

1. An electrolyte, characterized in that: The invention comprises an electrolyte salt, an organic solvent, and an additive, wherein the additive comprises a sulfonate-containing compound; the structural formula of the sulfonate-containing compound is any one selected from the following structures: 。 2. The electrolyte according to claim 1, characterized in that The additives include a first additive and a second additive; The first additive is a non-sulfonate additive, and the first additive is a non-sulfone additive; The second additive is a sulfonate additive, and the second additive is any one of the sulfonate-containing compounds shown in Formula I.

3. The electrolyte according to claim 2, characterized in that The first additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, phthaleinsulfonamide, and vinyl sulfate.

4. The electrolyte according to claim 2, characterized in that The number of additives in the electrolyte is no more than 3.

5. The electrolyte according to claim 2, characterized in that The amount of the second additive added to the electrolyte is 0.1-2% by mass.

6. The electrolyte according to claim 3, characterized in that The electrolyte salt is one or more of XPF6, XClO4, XBF4, XAsF6, XFSI, XTFSI, XBOB, XODFB, XCF3SO3, XPO2F2 or XOTFB; wherein X includes any one of Li, Na or K; and / or The organic solvent includes any one or a combination of at least two of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), 2,2-difluoroethyl acetate (DFEA), acetonitrile (AN), ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or tetrahydrofuran; and / or The concentration of the electrolyte salt in the electrolyte is 0.8-1.2 mol / L; and / or Based on the mass of the electrolyte as 100%, the content of the organic solvent is 58.5% to 92.7%; and / or The amount of the first additive added to the electrolyte is 1-8% by mass.

7. A battery, characterized in that: The electrolyte comprises a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and the electrolyte according to any one of claims 1 to 6.

8. The battery according to claim 7, characterized in that The negative electrode includes a negative electrode active material, and the negative electrode active material is selected from one or a combination of at least two of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, graphene, graphyne, metallic lithium / sodium / potassium, nanocarbon, carbon nanotubes, elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon / copper oxide composites, AG composites, silicon alloys, elemental tin, tin oxide compounds, tin-carbon composites, tin alloys, or lithium titanate; and / or The positive electrode comprises a positive electrode active material, and the positive electrode active material is selected from one or a combination of at least two of lithium nickel cobalt manganese oxide, NCA lithium nickel cobalt aluminum oxide, lithium-rich manganese, lithium cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate, layered oxide, sodium ferric fluorosulfate, and sodium ferric pyrophosphate; and / or The diaphragm is selected from any one of a polyolefin diaphragm and a composite ceramic membrane.

9. A battery module, characterized in that: A battery according to any one of claims 7 to 8 or an electrolyte according to any one of claims 1 to 6.

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