WO2023241147A1 - 一种电解液和含有该电解液的电池 - Google Patents

一种电解液和含有该电解液的电池 Download PDF

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WO2023241147A1
WO2023241147A1 PCT/CN2023/082296 CN2023082296W WO2023241147A1 WO 2023241147 A1 WO2023241147 A1 WO 2023241147A1 CN 2023082296 W CN2023082296 W CN 2023082296W WO 2023241147 A1 WO2023241147 A1 WO 2023241147A1
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substituted
electrolyte
unsubstituted
lithium
electrolyte solution
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PCT/CN2023/082296
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French (fr)
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朱辉
岳玉娟
刘建明
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珠海冠宇动力电池有限公司
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Publication of WO2023241147A1 publication Critical patent/WO2023241147A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present disclosure belongs to the technical field of lithium-ion batteries, and specifically relates to an electrolyte and a battery containing the electrolyte.
  • Lithium-ion batteries are widely used in 3C digital, power tools, aerospace, energy storage, power vehicles and other fields due to their high specific energy, no memory effect, and long cycle life.
  • Ternary cathode materials such as nickel-cobalt-manganese NCM ternary materials or nickel-cobalt-aluminum NCA ternary materials
  • Nion batteries have become the first choice for lithium-ion battery cathode active materials due to their good safety and low price.
  • the development and popularization of ion batteries has placed higher and higher requirements on the electrical performance of lithium-ion batteries.
  • ternary cathode materials face poor high-temperature storage, poor normal-high temperature cycle performance, and serious cycle gas production. This may be because as the charging voltage increases, the dissolution of transition metals in the ternary cathode material becomes more and more serious.
  • electrolyte matching there is also the problem of electrolyte matching. For example, conventional electrolyte will dissolve in the positive electrode of the battery at a high voltage of 4.45V. Surface oxidation and decomposition will accelerate the oxidation and decomposition of the electrolyte under high temperature conditions, and at the same time promote the deterioration reaction of the ternary cathode material.
  • the purpose of the present disclosure is to provide an electrolyte and a battery containing the electrolyte.
  • the present disclosure can effectively form an interface film that is tough, difficult to break, and has strong high temperature resistance on the surface of the positive and negative electrodes.
  • the oxidation resistance optimizes the cathode/electrolyte interface, reduces the activity of the cathode surface, inhibits the decomposition of the electrolyte under high voltage and high temperature conditions, thereby inhibiting the battery's Gas production during the cycle under high voltage and high temperature conditions; on the other hand, the interface film can effectively inhibit the dissolution of transition metals (Ni, Co, Al and Mn); in addition, the interfacial film generated by the electrolyte on the surface of the negative electrode has small impedance , has good conductive lithium ion channels.
  • the electrolyte of the present disclosure can significantly improve the high-temperature storage and normal-high temperature cycle performance of the battery in a high-voltage (4.45V and above) system, inhibit cyclic gas production, and also take into account low-temperature discharge. performance.
  • An electrolyte solution includes electrolyte salt, organic solvent and additives, the additives include ⁇ -carbonyl sulfide compounds and sulfonyldiimidazole compounds.
  • the electrolyte is used in a nickel-cobalt-manganese battery or a nickel-cobalt-aluminum battery.
  • the ⁇ -carbonyl sulfide compound is selected from at least one compound represented by Formula 1:
  • R 1 is a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group; if it is substituted, the substituent is halogen. or alkyl.
  • R 1 is a substituted or unsubstituted 5-20 membered heteroaryl group, a substituted or unsubstituted C 6-20 aryl group, a substituted or unsubstituted C 1-12 alkyl group or a substituted or unsubstituted C 1-12 alkyl group.
  • R 1 is a substituted or unsubstituted 5-10 membered heteroaryl, a substituted or unsubstituted C 6-10 aryl, a substituted or unsubstituted C 1-6 alkyl or a substituted or unsubstituted C 1-6 alkyl.
  • R 1 is a substituted or unsubstituted 5-6 membered heteroaryl, a substituted or unsubstituted C 6-8 aryl, a substituted or unsubstituted C 1-3 alkyl or a substituted or unsubstituted C 1-3 alkyl.
  • R1 is furyl, thienyl, isopropyl, cyclopropyl, 4-fluorophenyl or 4-trifluoromethylphenyl.
  • the ⁇ -carbonyl sulfide compound is selected from at least one compound A to compound F:
  • the sulfonyldiimidazole compound is selected from at least one compound represented by Formula 2:
  • R 4 and R 5 are the same or different, and are independently selected from the following groups: H, halogen, cyano, unsubstituted or optionally substituted by one, two or more R'a : C 1-6 alkyl , C 2-6 alkenyl, C 1-6 alkoxy, C 1-6 alkoxycarbonyl or sulfonic acid group (-SO 3 H); each R' a is the same or different, independently selected from halogen or C 1-6 alkyl.
  • R 4 and R 5 are the same or different, and are independently selected from H, propenyl, halogen, C 1-3 alkyl, methoxy, trifluoromethyl, C 1 -3 Alkoxycarbonyl, cyano or -SO 3 F.
  • the ⁇ -carbonylsulfide compounds and the sulfonyldiimidazole compounds can be purchased through commercial channels, or prepared by methods known in the art.
  • the mass of the ⁇ -carbonylsulfide ylide compound accounts for 0.1wt% to 0.5wt% of the total mass of the electrolyte, such as 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% , 0.5wt% or any point value in the range composed of the above two points.
  • the mass of the sulfonyldiimidazole compound accounts for 0.5wt% to 3wt% of the total mass of the electrolyte, for example, 0.5wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.7wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.7wt%, 3wt% or any point value in the range composed of the above two point values.
  • the sulfonyldiimidazole compound is selected from at least one of Compound 1 to Compound 6 shown below:
  • the electrolyte salt is selected from at least one of an electrolyte lithium salt, an electrolyte sodium salt, and an electrolyte magnesium salt.
  • the electrolyte lithium salt is selected from the group consisting of lithium hexafluorophosphate, lithium difluorophosphate, lithium bisoxaloborate, lithium difluorooxalate borate, lithium difluorooxalate phosphate, lithium tetrafluoroborate, lithium tetrafluorooxalate phosphate, At least one of lithium trifluoromethanesulfonimide and lithium bisfluorosulfonimide.
  • the mass of the electrolyte salt accounts for 13wt% to 20wt% of the total mass of the electrolyte, such as 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt % or any point value in the range composed of the above two point values.
  • the organic solvent is selected from the group consisting of propylene carbonate, ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, ⁇ -butyrolactone, sulfolane, Methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate At least two of ester, methyl butyrate, ethyl butyrate, propyl butyrate and butyl butyrate.
  • the present disclosure also provides a battery including the above electrolyte.
  • the battery is a lithium-ion battery.
  • the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.
  • the cathode sheet includes a cathode current collector and a cathode active material layer coated on one or both sides of the cathode current collector.
  • the cathode active material layer includes the cathode active material, a third a conductive agent and a first adhesive.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector.
  • the negative electrode active material layer includes the negative electrode active material, a third Second conductive agent and second adhesive agent.
  • the mass percentage of each component in the positive active material layer is: 80wt% to 99.8wt% of the positive active material, 0.1wt% to 10wt% of the first conductive agent and 0.1wt% to 10wt% of the first binder.
  • the mass percentage of each component in the positive active material layer is: 90wt% to 99.6wt% of the positive active material, 0.2wt% to 5wt% of the first conductive agent, and 0.2wt%. ⁇ 5wt% of the first binder.
  • the mass percentage of each component in the negative active material layer is: 80wt% to 99.8wt% of the negative active material, 0.1wt% to 10wt% of the second conductive agent and 0.1wt% to 10wt% of the second binder.
  • the mass percentage of each component in the negative active material layer is: 90wt% to 99.6wt% of the negative active material, 0.2wt% to 5wt% of the second conductive agent, and 0.2wt%. ⁇ 5wt% of the second binder.
  • the first conductive agent and the second conductive agent are each independently selected from conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes and metal powder. At least one.
  • the first binder and the second binder are each independently selected from at least one of sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene and polyethylene oxide. kind.
  • the cathode active material is selected from LiNixCoyMnzM1 (1-xyz) O2 or LiNixCoyAlzM2 (1-xyz) O2 , where M1 is any one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, M 2 is Mn, Mg, Cu, Zn, Sn, B, Ga, Cr, Sr, V Any one of Ti and Ti, 0.5 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.5, 0 ⁇ z ⁇ 0.5, x+y+z ⁇ 1.
  • the negative active material is selected from at least one of artificial graphite, natural graphite, hard carbon, soft carbon, mesocarbon microspheres, silicon-based negative electrode materials and lithium-containing metal composite oxide materials. A sort of.
  • the charging cut-off voltage of the battery is 4.45V and above.
  • the present disclosure provides an electrolyte solution and a battery containing the electrolyte solution.
  • the combination of ⁇ -carbonyl sulfide ylide compounds and sulfonyldiimidazole compounds can effectively form an interface film that is tough, difficult to break, and has strong high temperature resistance on the surface of the positive and negative electrodes, improving electrolysis.
  • the oxidation resistance of the liquid optimizes the cathode/electrolyte interface, reduces the surface activity of the cathode, inhibits the decomposition of the electrolyte under high voltage and high temperature conditions, thereby inhibiting the gas production during battery cycling under high voltage and high temperature conditions, and
  • This interface film can effectively inhibit the dissolution of transition metals (Ni, Co, Al and Mn).
  • sulfonyldiimidazole compounds are also conducive to forming a uniform and dense interface film on the surface of the positive electrode active material, reducing the phenomenon of uneven insertion of positive electrode Li + .
  • sulfonyldiimidazole compounds can also be reduced (reduced) on the surface of the negative electrode material.
  • the potential is: 1.5V vs Li + /Li) to form a dense and stable SEI film, reducing the reduction and decomposition of the electrolyte on the surface of the negative electrode material.
  • the two simultaneously form an interfacial film through redox reactions at the positive and negative electrode interfaces prior to the solvent, optimizing the composition of the positive and negative electrode interface film, improving the thermal stability of the interface film and reducing the migration resistance of lithium ions, and synergize with each other.
  • NMP N-methylpyrrolidone
  • the negative active material artificial graphite, thickener sodium carboxymethylcellulose (CMC-Na), binder styrene-butadiene rubber, conductive agent acetylene black and conductive agent single-walled carbon nanotubes (SWCNT) are used in a weight ratio of 95.9: Mix 1:1.8:1:0.3, add deionized water, and obtain a negative electrode slurry under the action of a vacuum mixer; coat the negative electrode slurry evenly on a copper foil with a thickness of 8 ⁇ m; dry it (temperature: 85°C , time: 5h), rolling and die-cutting to obtain the negative electrode sheet.
  • the required lithium-ion batteries are obtained through vacuum packaging, standing, formation, second sealing, sorting and other processes.
  • the lithium ion batteries of Comparative Examples 1 to 2 and Examples 1 to 15 were all prepared according to the above preparation method.
  • the specific combinations and contents of lithium salts and additives are as shown in Table 1.
  • the interface film composed of , LiOCO 2 R and other components improves the oxidation resistance of the electrolyte, optimizes the positive electrode/electrolyte interface, reduces the surface activity of the positive electrode, inhibits the decomposition of the electrolyte under the high voltage and high temperature conditions of 4.45V, and thereby inhibits Lithium-ion batteries produce gas during high-temperature and high-voltage cycles, and this interface film can effectively inhibit the dissolution of transition metals (Ni, Co, and Mn); in addition, sulfonyldiimidazole compounds are also beneficial to forming a uniform and dense layer on the surface of the cathode active material.
  • the interface film reduces the uneven embedding of Li + in the positive electrode.
  • sulfonyldiimidazole compounds can also be reduced on the surface of the negative electrode material (reduction potential: 1.5V vs Li + /Li) to form a dense and stable SEI film, reducing electrolysis The reductive decomposition of the liquid on the surface of the negative electrode material.
  • the two simultaneously form an interfacial film through redox reactions at the positive and negative electrode interfaces prior to the solvent, optimizing the composition of the positive and negative electrode interface film, improving the thermal stability of the interface film and reducing the migration resistance of lithium ions, and synergize with each other.
  • Example 2 because the content of ⁇ -carbonylsulfide ylide compounds is relatively low, the low-temperature discharge, cycle and storage performance are all reduced. In Example 3, because the content of ⁇ -carbonylsulfide ylide compounds is too high, the impedance increases, and the normal temperature cycle and low-temperature discharge performance decreases. In Example 4, because the content of sulfonyldiimidazole compounds is too low, the high-temperature cycle performance is reduced. In Example 5, because the content of sulfonyldiimidazole compounds is too high, the impedance increases, and the normal temperature cycle and low temperature discharge performance decreases.
  • Comparative Example 1 does not contain ⁇ -carbonyl sulfide ylide compounds, which leads to a decrease in cycle, deterioration in low-temperature discharge and high-temperature storage.
  • Comparative Example 2 does not contain sulfonyldiimidazole compounds, resulting in cycle decline, low-temperature discharge, and high-temperature storage degradation.

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Abstract

本公开提供了一种电解液和含有该电解液的电池。本公开提供的电解液中，α-羰基硫叶立德类化合物和硫酰二咪唑类化合物的组合能有效地在正负极表面形成富有韧性、不易破裂、耐高温性能强的界面膜，提高了电解液的耐氧化性，优化了正极/电解液界面，降低了正极的表面活性，抑制了电解液在高电压高温条件下的分解，进而抑制了电池在高电压高温条件下循环过程中产气，而且该界面膜可有效抑制过渡金属(Ni、Co、Al和Mn)溶出；显著提高了电池于高电压(4.45V及以上)体系下的高温存储、循环性能、低温放电性能。

Description

一种电解液和含有该电解液的电池 技术领域
本公开属于锂离子电池技术领域，具体涉及到一种电解液和含有该电解液的电池。
背景技术
锂离子电池由于具有高比能量、无记忆效应、循环寿命长等优点被广泛应用于3C数码、电动工具、航天、储能、动力汽车等领域。三元正极材料(如镍钴锰NCM三元材料或镍钴铝NCA三元材料)由于安全性好以及价格低廉，已经成为锂离子电池正极活性物质的首选，但随着更高电压体系的锂离子电池的发展与普及，对锂离子电池的电性能要求越来越高。
目前，锂离子电池于高电压(4.45V及以上)体系下存在一些挑战：三元正极材料面临高温存储差、常高温循环性能差以及循环产气严重的问题。这可能是因为随着充电电压的提高，三元正极材料中过渡金属的溶出越来越严重，同时还存在着电解液匹配的问题，如常规的电解液在4.45V高电压下会在电池正极表面氧化分解，在高温条件下会加速电解液的氧化分解，同时促使三元正极材料的恶化反应。
因此，亟需开发一种能有效抑制循环产气，提高电池于高电压(4.45V及以上)体系下的高温存储和常高温循环性能的电解液，进而保证三元锂离子电池电性能的优良发挥。
发明内容
为了改善现有技术的不足，本公开的目的是提供一种电解液和含有该电解液的电池。本公开通过α-羰基硫叶立德类化合物和硫酰二咪唑类化合物的组合使用，能有效地在正负极表面形成富有韧性、不易破裂以及耐高温性能强的界面膜，一方面提高了电解液的耐氧化性，优化了正极/电解液界面，降低了正极表面的活性，抑制了电解液在高电压高温条件下的分解，进而抑制了电池在 高电压高温条件下循环过程中的产气；另一方面该界面膜可有效抑制过渡金属(Ni、Co、Al和Mn)的溶出；另外所述电解液在负极表面生成的界面膜的阻抗小，具有良好的传导锂离子通道，因此，本公开的电解液能明显提高电池于高电压(4.45V及以上)体系下的高温存储和常高温循环性能，抑制循环产气，同时还兼顾低温放电性能。
本公开目的是通过如下技术方案实现的：
一种电解液，所述电解液包括电解质盐、有机溶剂和添加剂，所述添加剂包括α-羰基硫叶立德类化合物和硫酰二咪唑类化合物。
根据本公开的实施方式，所述电解液用于镍钴锰电池或镍钴铝电池。
根据本公开的实施方式，所述α-羰基硫叶立德类化合物选自式1所示的化合物中的至少一种：
式1中，R1为取代或未取代的杂芳基、取代或未取代的芳基、取代或未取代的烷基或取代或未取代的环烷基；若为取代时，取代基为卤素或烷基。
根据本公开的实施方式，R1为取代或未取代的5-20元杂芳基、取代或未取代的C6-20芳基、取代或未取代的C1-12烷基或取代或未取代的C3-20环烷基；若为取代时，取代基为卤素或C1-12烷基。
根据本公开的实施方式，R1为取代或未取代的5-10元杂芳基、取代或未取代的C6-10芳基、取代或未取代的C1-6烷基或取代或未取代的C3-10环烷基；若为取代时，取代基为卤素或C1-6烷基。
根据本公开的实施方式，R1为取代或未取代的5-6元杂芳基、取代或未取代的C6-8芳基、取代或未取代的C1-3烷基或取代或未取代的C3-6环烷基；若为取代时，取代基为卤素或C1-6烷基。
根据本公开的实施方式，R1为呋喃基、噻吩基、异丙基、环丙基、4-氟苯基或4-三氟甲基苯基。
根据本公开的实施方式，所述α-羰基硫叶立德类化合物选自化合物A～化合物F中的至少一种：
根据本公开的实施方式，所述硫酰二咪唑类化合物选自式2所示的化合物中的至少一种：
式2中，n1为0、1、2或3；n2为0、1、2或3；
R4和R5相同或不同，彼此独立地选自H、卤素、氰基、无取代或任选被一个、两个或更多个R’a取代的下列基团：C1-6烷基、C2-6烯基、C1-6烷氧基、C1-6烷氧羰基或磺酸基(-SO3H)；每一个R’a相同或不同，彼此独立地选自卤素或C1-6烷基。
根据本公开的实施方案，式2中，R4和R5相同或不同，彼此独立地选自H、丙烯基、卤素、C1-3烷基、甲氧基、三氟甲基、C1-3烷氧羰基、氰基或-SO3F。
根据本公开的实施方式，所述α-羰基硫叶立德类化合物和所述硫酰二咪唑类化合物可以通过商业途径购买后获得，或者通过本领域已知的方法制备得到。
根据本公开的实施方式，所述α-羰基硫叶立德类化合物的质量占所述电解液总质量的0.1wt％～0.5wt％，如0.1wt％、0.2wt％、0.3wt％、0.4wt％、0.5wt％或上述两两点值组成的范围中的任意点值。
根据本公开的实施方式，所述硫酰二咪唑类化合物的质量占所述电解液总质量的0.5wt％～3wt％，例如为0.5wt％、1.0wt％、1.2wt％、1.5wt％、1.7wt％、1.8wt％、2wt％、2.2wt％、2.4wt％、2.5wt％、2.7wt％、3wt％或上述两两点值组成的范围中的任意点值。
根据本公开的实施方式，所述硫酰二咪唑类化合物选自如下所示的化合物1～化合物6中的至少一种：

根据本公开的实施方式，所述电解质盐选自电解质锂盐、电解质钠盐和电解质镁盐中的至少一种。
根据本公开的实施方式，所述电解质锂盐选自六氟磷酸锂、二氟磷酸锂、双草酸硼酸锂、二氟草酸硼酸锂、二氟草酸磷酸锂、四氟硼酸锂、四氟草酸磷酸锂、双三氟甲基磺酰亚胺锂和双氟磺酰亚胺锂中的至少一种。
根据本公开的实施方式，所述电解质盐的质量占所述电解液总质量的13wt％～20wt％，例如13wt％、14wt％、15wt％、16wt％、17wt％、18wt％、19wt％、20wt％或上述两两点值组成的范围中的任意点值。
根据本公开的实施方式，所述有机溶剂选自碳酸丙烯酯、碳酸甲乙酯、碳酸乙烯酯、碳酸二甲酯、碳酸二乙酯、氟代碳酸乙烯酯、γ-丁内酯、环丁砜、甲酸甲酯、甲酸乙酯、甲酸丙酯、甲酸丁酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯、丁酸丙酯和丁酸丁酯中的至少两种。
本公开还提供一种电池，所述电池包括上述电解液。
根据本公开的实施方式，所述电池为锂离子电池。
根据本公开的实施方式，所述电池还包括含有正极活性物质的正极片、含有负极活性物质的负极片和隔离膜。
根据本公开的实施方式，所述正极片包括正极集流体和涂覆在所述正极集流体一侧或两侧表面的正极活性物质层，所述正极活性物质层包括所述正极活性物质、第一导电剂和第一粘结剂。
根据本公开的实施方式，所述负极片包括负极集流体和涂覆在所述负极集流体一侧或两侧表面的负极活性物质层，所述负极活性物质层包括所述负极活性物质、第二导电剂和第二粘结剂。
根据本公开的实施方式，所述正极活性物质层中各组分的质量百分含量为：80wt％～99.8wt％的所述正极活性物质、0.1wt％～10wt％的所述第一导电剂和0.1wt％～10wt％的所述第一粘结剂。
优选地，所述正极活性物质层中各组分的质量百分含量为：90wt％～99.6wt％的所述正极活性物质、0.2wt％～5wt％的所述第一导电剂和0.2wt％～5wt％的所述第一粘结剂。
根据本公开的实施方式，所述负极活性物质层中各组分的质量百分含量为：80wt％～99.8wt％的所述负极活性物质、0.1wt％～10wt％的所述第二导电剂和0.1wt％～10wt％的所述第二粘结剂。
优选地，所述负极活性物质层中各组分的质量百分含量为：90wt％～99.6wt％的所述负极活性物质、0.2wt％～5wt％的所述第二导电剂和0.2wt％～5wt％的所述第二粘结剂。
根据本公开的实施方式，所述第一导电剂和所述第二导电剂各自独立地选自导电炭黑、乙炔黑、科琴黑、导电石墨、导电碳纤维、碳纳米管和金属粉中的至少一种。
根据本公开的实施方式，所述第一粘结剂和所述第二粘结剂各自独立地选自羧甲基纤维素钠、丁苯胶乳、聚四氟乙烯和聚氧化乙烯中的至少一种。
根据本公开的实施方式，所述正极活性物质选自LiNixCoyMnzM1 (1-x-y-z)O2或LiNixCoyAlzM2 (1-x-y-z)O2，其中，M1为Mg、Cu、Zn、Al、Sn、B、Ga、Cr、Sr、V和Ti中的任意一种，M2为Mn、Mg、Cu、Zn、Sn、B、Ga、Cr、Sr、V和Ti中的任意一种，0.5≤x<1，0<y<0.5，0<z<0.5，x+y+z≤1。
根据本公开的实施方式，所述负极活性物质选自人造石墨、天然石墨、硬炭、软炭、中间相碳微球、硅基负极材料和含锂金属复合氧化物材料中的至少 一种。
根据本公开的实施方式，所述电池的充电截止电压在4.45V及以上。
本公开的有益效果：
本公开提供了一种电解液和含有该电解液的电池。本公开提供的电解液中，α-羰基硫叶立德类化合物和硫酰二咪唑类化合物的组合能有效地在正负极表面形成富有韧性、不易破裂以及耐高温性能强的界面膜，提高了电解液的耐氧化性，优化了正极/电解液界面，降低了正极的表面活性，抑制了电解液在高电压高温条件下的分解，进而抑制了电池在高电压高温条件下循环过程中产气，而且该界面膜可有效抑制过渡金属(Ni、Co、Al和Mn)溶出。此外，硫酰二咪唑类化合物还有利于在正极活性物质表面形成均匀致密的界面膜，减少了正极Li+嵌入不均匀的现象，同时硫酰二咪唑类化合物还可以在负极材料表面还原(还原电位为：1.5V vs Li+/Li)形成致密稳定的SEI膜，减少电解液在负极材料表面的还原分解。总之，二者同时在正负极界面优先于溶剂发生氧化还原反应形成界面膜，优化了正负极界面膜成分，改善了界面膜的热稳定性同时降低了锂离子的迁移阻力，相互协同，显著提高了电池于高电压(4.45V及以上)体系下的高温存储、循环性能和低温放电性能。
具体实施方式
下文将结合具体实施例对本公开做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本公开，而不应被解释为对本公开保护范围的限制。凡基于本公开上述内容所实现的技术均涵盖在本公开旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
锂离子电池制备
(1)正极片制备
将正极活性物质镍钴锰酸锂三元材料LiNi0.5Co0.2Mn0.3O2(NCM523)、粘结剂聚偏氟乙烯(PVDF)和导电剂乙炔黑按照重量比为96.5:2:1.5进行混合，加入 N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌，直至混合体系成均一流动性的正极浆料；将该正极浆料均匀涂覆在厚度为12μm铝箔上；将上述涂覆好的铝箔在5段不同温度梯度的烘箱烘烤后，再将其在120℃的烘箱干燥8h，然后经过辊压、模切后得到正极片。
(2)负极片制备
将负极活性物质人造石墨、增稠剂羧甲基纤维素钠(CMC-Na)、粘结剂丁苯橡胶、导电剂乙炔黑和导电剂单壁碳纳米管(SWCNT)按照重量比为95.9:1:1.8:1:0.3进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料；将该负极浆料均匀涂覆在厚度为8μm的铜箔上；经烘干(温度：85℃，时间：5h)、辊压、模切后得到负极片。
(3)电解液制备
在充满氩气的手套箱(水分<10ppm，氧分<1ppm)中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)以25:60:15的质量比混合均匀，在混合溶液中快速加入基于电解液总质量百分比为14.5wt％充分干燥的六氟磷酸锂以及添加剂(具体用量和选择如表1所示)，搅拌均匀得到电解液。
(4)隔膜的制备
选用8μm厚的涂层聚乙烯隔膜。
(5)锂离子电池的制备
将上述准备的正极片、隔膜和负极片通过卷绕得到未注液的裸电芯；将该裸电芯置于外包装箔中，将上述制备好的电解液注入到干燥后的裸电芯中，经过真空封装、静置、化成、二封、分选等工序，获得所需的锂离子电池。
对比例1～2及实施例1～15锂离子电池均按照上述制备方法进行制备，具体锂盐和添加剂组合及含量如表1所示。
对比例1～2及实施例1～15锂离子电池的电化学性能测试结果如表2所示。
表1对比例1～2及实施例1～15锂离子电池的电解液的组成

(1)25℃循环实验：将上述实施例和对比例所得电池置于(25±2)℃环境中，静置2～3小时，待电池本体达到(25±2)℃时，电池按照1C恒流恒压充电至4.45V截止电流为0.05C，电池充满电后搁置5min，再以1C恒流放电至截止电压3.0V，记录前3次循环的最高放电容量为初始容量Q，当循环达到所需的次数时，记录电池的最后一次的放电容量Q1，记录结果如表2。
其中用到的计算公式如下：容量保持率(％)＝Q1/Q×100％。
(2)45℃循环实验：将上述实施例和对比例所得电池置于(45±2)℃环境中，静置2～3小时，待电池本体达到(45±2)℃时，电池按照1C恒流恒压充电至4.45V截止电流为0.05C，电池充满电后搁置5min，再以1C恒流放电至截止电压3.0V，记录前3次循环的最高放电容量为初始容量Q，当循环达到所需的次数时，记录电池的最后一次的放电容量Q1，记录结果如表2。
其中用到的计算公式如下：容量保持率(％)＝Q1/Q×100％。
(3)低温放电性能测试：在常温(25℃)条件下，对锂离子电池进行一次0.5C/0.5C充电和放电(放电容量记为C0)，上限电压为4.45V，然后在0.5C恒流恒压条件下将电池充电至4.45V；将锂离子电池置于-20℃低温箱中搁置4h，在-20℃下 进行0.5C放电(放电容量记为C1)，记录结果如表2。
其中用到的计算公式如下：低温放电容量保持率(％)＝Q1/Q0×100％。
(4)高温存储测试：在常温(25℃)条件下，对锂离子电池进行一次0.3C/0.3C充电和放电(电池放电容量记录为C0)，上限电压为4.45V；将电池放置于60℃恒温箱中搁置30天，取出电池，将电池放置于25℃环境中，进行0.3C放电，放电容量记录为C1；然后对锂离子电池进行一次0.3C/0.3C充电和放电(电池放电容量记录为C2)，利用下面公式计算锂离子电池的容量保持率和容量恢复率；
容量保持率＝(C1/C0)*100％；
容量恢复率＝(C2/C0)*100％；
记录结果如表2。
高温存储厚度膨胀测试：在常温(25℃)条件下，对锂离子电池进行一次0.3C/0.3C充电和放电，上限电压为4.45V，放电结束后测量电池厚度，记录为D0；将电池放置于60℃烘箱中搁置30天，取出电池，测量电池厚度，记录为D1。
厚度膨胀率＝((D1-D0)/D0)*100％；
记录结果如表2。
表2对比例1～2及实施例1～15锂离子电池的性能测试结果

综合上述实施例和对比例可知，实施例1～15提供的电解液中α-羰基硫叶立德类化合物和硫酰二咪唑类化合物的组合能有效地在正负极表面形成富含Li2SO3、LiOCO2R等成分的界面膜，提高了电解液的耐氧化性，优化了正极/电解液界面，降低了正极的表面活性，抑制电解液在4.45V高电压高温条件下的分解，进而抑制锂离子电池在高温高电压循环过程中产气，而且该界面膜可有效抑制过渡金属(Ni、Co和Mn)溶出；此外，硫酰二咪唑类化合物还有利于在正极活性物质表面形成均匀致密的界面膜，减少了正极Li+嵌入不均匀的现象，同时硫酰二咪唑类化合物还可以在负极材料表面还原(还原电位为：1.5V vs Li+/Li)形成致密稳定的SEI膜，减少电解液在负极材料表面的还原分解。总之，二者同时在正负极界面优先于溶剂发生氧化还原反应形成界面膜，优化了正负极界面膜成分，改善了界面膜的热稳定性同时降低了锂离子的迁移阻力，相互协同，显著提高了电池于高电压(4.45V及以上)体系下的高温存储、循环性能和低温放电性能。
实施例2中因为α-羰基硫叶立德类化合物含量偏少，导致低温放电、循环和存储性能均有下降。实施例3中因为α-羰基硫叶立德类化合物含量偏多，导致阻抗增大，常温循环和低温放电性能下降。实施例4中因为硫酰二咪唑类化合物含量偏少，导致高温循环性能下降。实施例5中因为硫酰二咪唑类化合物含量偏多，导致阻抗增大，常温循环和低温放电性能下降。
对比例1中因为不含有α-羰基硫叶立德类化合物含量，导致循环下降、低温放电和高温存储均有劣化。对比例2中因为不含有硫酰二咪唑类化合物，导致循环下降、低温放电和高温存储均有劣化。
以上，对本公开的实施方式进行了说明。但是，本公开不限定于上述实施方式。凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应 包含在本公开的保护范围之内。

Claims (15)

  1. 一种电解液，其特征在于，所述电解液包括电解质盐、有机溶剂和添加剂，所述添加剂包括α-羰基硫叶立德类化合物和硫酰二咪唑类化合物。
  2. 根据权利要求1所述的电解液，其特征在于，所述α-羰基硫叶立德类化合物选自式1所示的化合物中的至少一种：
    式1中，R1为取代或未取代的杂芳基、取代或未取代的芳基、取代或未取代的烷基或取代或未取代的环烷基；若为取代时，取代基为卤素或烷基。
  3. 根据权利要求2所述的电解液，其特征在于，R1为取代或未取代的5-20元杂芳基、取代或未取代的C6-20芳基、取代或未取代的C1-12烷基或取代或未取代的C3-20环烷基；若为取代时，取代基为卤素或C1-12烷基。
  4. 根据权利要求2或3所述的电解液，其特征在于，R1为取代或未取代的5-10元杂芳基、取代或未取代的C6-10芳基、取代或未取代的C1-6烷基或取代或未取代的C3-10环烷基；若为取代时，取代基为卤素或C1-6烷基。
  5. 根据权利要求2-4中任意一项所述的电解液，其特征在于，R1为取代或未取代的5-6元杂芳基、取代或未取代的C6-8芳基、取代或未取代的C1-3烷基或取代或未取代的C3-6环烷基；若为取代时，取代基为卤素或C1-6烷基。
  6. 根据权利要求1-5中任意一项所述的电解液，其特征在于，所述α-羰基硫叶立德类化合物选自化合物A～化合物F中的至少一种：

  7. 根据权利要求1-6中任意一项所述的电解液，其特征在于，所述硫酰二咪唑类化合物选自式2所示的化合物中的至少一种：
    式2中，n1为0、1、2或3；n2为0、1、2或3；
    R4和R5相同或不同，彼此独立地选自H、卤素、氰基、无取代或任选被一个、两个或更多个R’a取代的下列基团：C1-6烷基、C2-6烯基、C1-6烷氧基、C1-6烷氧羰基或磺酸基(-SO3H)；每一个R’a相同或不同，彼此独立地选自卤素或C1-6烷基。
  8. 根据权利要求7所述的电解液，其特征在于，式2中，R4和R5相同或不同，彼此独立地选自H、丙烯基、卤素、C1-3烷基、甲氧基、三氟甲基、C1-3烷氧羰基、氰基或-SO3F。
  9. 根据权利要求1-8中任意一项所述的电解液，其特征在于，所述α-羰基硫叶立德类化合物的质量占所述电解液总质量的0.1wt％～0.5wt％。
  10. 根据权利要求1-9中任意一项所述的电解液，其特征在于，所述硫酰二咪唑类化合物的质量占所述电解液总质量的0.5wt％～3wt％。
  11. 根据权利要求1-10中任意一项所述的电解液，其特征在于，所述硫酰二咪唑类化合物选自如下所示的化合物1～化合物6中的至少一种：
  12. 根据权利要求1-11中任意一项所述的电解液，其特征在于，所述电解质盐选自电解质锂盐、电解质钠盐和电解质镁盐中的至少一种；
    优选地，所述电解质锂盐选自六氟磷酸锂、二氟磷酸锂、双草酸硼酸锂、二氟草酸硼酸锂、二氟草酸磷酸锂、四氟硼酸锂、四氟草酸磷酸锂、双三氟甲基磺酰亚胺锂和双氟磺酰亚胺锂中的至少一种；
    优选地，所述电解质盐的质量占所述电解液总质量的13wt％～20wt％。
  13. 根据权利要求1-12中任意一项所述的电解液，其特征在于，所述有机溶剂选自碳酸丙烯酯、碳酸甲乙酯、碳酸乙烯酯、碳酸二甲酯、碳酸二乙酯、氟代碳酸乙烯酯、γ-丁内酯、环丁砜、甲酸甲酯、甲酸乙酯、甲酸丙酯、甲酸丁酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯、丁酸丙酯和丁酸丁酯中的至少两种。
  14. 一种电池，其特征在于，所述电池包括权利要求1-13中任意一项所 述的电解液。
  15. 根据权利要求14所述的电池，其特征在于，所述电池还包括含有正极活性材料的正极片，所述正极活性材料选自LiNixCoyMnzM1 (1-x-y-z)O2或LiNixCoyAlzM2 (1-x-y-z)O2，其中，M1为Mg、Cu、Zn、Al、Sn、B、Ga、Cr、Sr、V和Ti中的任意一种，M2为Mn、Mg、Cu、Zn、Sn、B、Ga、Cr、Sr、V和Ti中的任意一种，0.5≤x<1，0<y<0.5，0<z<0.5，x+y+z≤1；
    优选地，所述电池的充电截止电压在4.45V及以上。
PCT/CN2023/082296 2022-06-17 2023-03-17 一种电解液和含有该电解液的电池 WO2023241147A1 (zh)

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