WO2024001427A1 - 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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WO2024001427A1
WO2024001427A1 PCT/CN2023/088441 CN2023088441W WO2024001427A1 WO 2024001427 A1 WO2024001427 A1 WO 2024001427A1 CN 2023088441 W CN2023088441 W CN 2023088441W WO 2024001427 A1 WO2024001427 A1 WO 2024001427A1
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electrolyte
substituted
group
alkyl
unsubstituted
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PCT/CN2023/088441
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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 WO2024001427A1 publication Critical patent/WO2024001427A1/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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • 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
    • 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 a common secondary battery.
  • the cathode materials of commercial lithium-ion batteries mainly include lithium manganese oxide, lithium cobalt oxide, ternary materials, and lithium iron phosphate. Their charging cut-off voltage generally does not exceed 4.2V. With the advancement of technology and the continuous development of the market, Improving the energy density of lithium-ion batteries is increasingly important and urgent.
  • high-voltage (4.35V ⁇ 5V) cathode materials are one of the more popular research directions. It achieves high energy density of batteries by increasing the charging depth of cathode active materials.
  • electrolyte as an important component of lithium-ion batteries, has a significant impact on the battery's charge and discharge cycle and other performance.
  • the electrolyte determines the migration rate of lithium ions (Li + ) in the liquid phase, and also participates in the formation of the solid electrolyte interface (SEI) film, which plays a key role in the performance of the SEI film.
  • SEI solid electrolyte interface
  • the electrolyte may cause Lithium-ion batteries have poor high-temperature storage performance, poor high-temperature cycle performance, and poor room-temperature cycle performance; at the same time, the viscosity of the electrolyte increases at low temperatures, the conductivity decreases, and the SEI film resistance increases, so the electrolyte may also cause lithium ion
  • the low-temperature discharge performance of the battery is poor, and there is even a risk of low-temperature lithium precipitation. Therefore, there is an urgent need to develop an electrolyte with excellent performance in all aspects to meet the requirements of high energy density ternary material batteries.
  • the purpose of the present disclosure is to provide an electrolyte and a battery containing the electrolyte.
  • the present disclosure is used to improve high-voltage batteries above 4.35V (especially nickel-cobalt-manganese ternary material batteries or nickel-cobalt-aluminum ternary materials) by introducing nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups into the electrolyte. material battery) while inhibiting lithium deposition in the negative electrode.
  • the formation of a single fluorinated cyclic carbonate in the electrolyte can be effectively avoided.
  • the further consumption of quasi-compounds and the reaction between the electrolyte and the negative electrode interface further enhance the high-temperature cycle performance, room temperature cycle performance, low-temperature discharge performance and rate performance of high-voltage batteries above 4.35V while inhibiting lithium deposition in the negative electrode.
  • An electrolyte solution includes an electrolyte salt, an organic solvent and an additive, and the additive includes a nitrogen-containing heterocyclic compound containing a sulfonate ester group or a sulfone group.
  • the electrolyte is used in a nickel-cobalt-manganese ternary material battery or a nickel-cobalt-aluminum ternary material battery.
  • the nitrogen-containing heterocyclic compound containing a sulfonate ester group or a sulfone group includes a sulfonate ester group or a sulfone group, and the sulfur and nitrogen in the sulfonate ester group or sulfone group form a heterocyclic structure.
  • the electrolyte solution further includes a fluorinated cyclic carbonate compound.
  • the fluorinated cyclic carbonate compound includes a carbonate group, and the carbonate group and the alkyl group form a cyclic structure.
  • the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of the compounds represented by Formula 1:
  • X is -O- or -N(R 2 )-;
  • R 1 is halogen, substituted or unsubstituted alkyl, if substituted, the substituent is halogen or alkyl;
  • R 2 is a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group, and if substituted, the substituent is halogen or alkyl.
  • R 1 is halogen, substituted or unsubstituted C 1-12 alkyl, if substituted, the substituent is halogen, C 1-12 alkyl;
  • R 2 is a substituted or unsubstituted C 6-20 aryl group or a substituted or unsubstituted C 1-12 alkyl group. If substituted, the substituent is halogen or C 1-12 alkyl group.
  • R 1 is halogen, substituted or unsubstituted C 1-6 alkyl, if substituted, the substituent is halogen, C 1-6 alkyl;
  • R 2 is a substituted or unsubstituted C 6-10 aryl group or a substituted or unsubstituted C 1-6 alkyl group. If substituted, the substituent is halogen or C 1-6 alkyl group.
  • R 1 is halogen, substituted or unsubstituted C 1-3 alkyl, if substituted, the substituent is halogen, C 1-3 alkyl;
  • R 2 is a substituted or unsubstituted phenyl group, a substituted or unsubstituted C 1-3 alkyl group, and if substituted, the substituent is halogen or C 1-3 alkyl group.
  • the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is selected from at least one of compound A to compound H:
  • the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group can be purchased through commercial channels, or prepared by methods known in the art.
  • the quality of the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is The amount accounts for 0.05wt% to 1wt% of the total mass of the electrolyte, preferably 0.1 to 0.5wt%, such as 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt% , 0.7wt%, 0.8wt%, 0.9wt%, 1wt% or any point value in the range composed of the above two point values.
  • the fluorinated cyclic carbonate compound is selected from at least one compound represented by Formula 2:
  • R 3 and R 4 are the same or different, independently selected from H, F, substituted or unsubstituted alkyl, and contain at least one F atom. If substituted, the substituent is F, alkyl.
  • R 3 and R 4 are the same or different, independently selected from H, F, substituted or unsubstituted C 1-6 alkyl, and contain at least one F atom, if When substituted, the substituent is F, C 1-6 alkyl.
  • R 3 and R 4 are the same or different, independently selected from H, F, substituted or unsubstituted C 1-3 alkyl, and contain at least one F atom, if When substituted, the substituent is F, C 1-3 alkyl.
  • the fluorinated cyclic carbonate compound can be purchased commercially or prepared by methods known in the art.
  • the mass of the fluorinated cyclic carbonate compound accounts for 0.5wt% to 12wt% of the total mass of the electrolyte, preferably 1wt% to 10wt%, for example, 0.5wt%, 1wt%, 2wt %, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt% or any point value in the range composed of the above two point values.
  • the fluorinated cyclic carbonate 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 electrolyte lithium salt, electrolyte sodium salt, electrolyte magnesium salt, and the like.
  • 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 13 to 20 wt% of the total mass of the electrolyte, such as 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt% or 20 wt%.
  • 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, which includes the above-mentioned electrolyte.
  • the battery is a lithium-ion battery.
  • the battery is a nickel-cobalt-manganese ternary battery or a nickel-cobalt-aluminum ternary 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 positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector.
  • the positive electrode active material layer includes a positive electrode active material, a conductive agent and a binding agent. agent.
  • 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 a negative electrode active material, a conductive agent and a binder. agent.
  • the mass percentage of each component in the positive active material layer is: 80wt% ⁇ 99.8wt% positive active material, 0.1wt% ⁇ 10wt% conductive agent, 0.1wt% ⁇ 10wt % 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 conductive agent, and 0.2wt% to 5wt% of the binder. agent.
  • the mass percentage of each component in the negative active material layer is: 80wt% ⁇ 99.8wt% negative active material, 0.1wt% ⁇ 10wt% conductive agent, 0.1wt% ⁇ 10wt % binder.
  • the mass percentage of each component in the negative active material layer is: 90wt% ⁇ 99.6wt% negative active material, 0.2wt% ⁇ 5wt% conductive agent, 0.2wt% ⁇ 5wt% binding agent. agent.
  • the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes and metal powder.
  • the binder is selected from at least one selected from sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene and polyethylene oxide.
  • 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 and Ti, 0.5 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 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.
  • the charging cut-off voltage of the battery is 4.35V and above.
  • the present disclosure provides an electrolyte solution and a battery containing the electrolyte solution.
  • the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group is a bifunctional additive. There are lone electron pairs on its N atoms.
  • the electrolyte After a small amount is added to the electrolyte, it can exhibit weak Lewis alkalinity can form complexes (such as six-ligand complexes) with other components in the electrolyte (such as PF 5 , phosphorus pentafluoride), reduce the acidity and reactivity of the electrolyte, and inhibit free acid in the electrolyte increase; at the same time, nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups can form a large amount of LiSO 3 , ROSO 2 Li, Li x N y O z (0 ⁇ x ⁇ 3, 0 ⁇ y ⁇ 1, 2 ⁇ z ⁇ 3), the outer interface film has good high temperature resistance and low impedance, which is conducive to the migration of lithium ions and can improve the high temperature cycle performance and normal temperature cycle performance of high voltage batteries. , low-temperature discharge performance and rate performance while suppressing lithium evolution in the negative electrode.
  • complexes such as six-ligand complexes
  • NMP N-methylpyrrolidone
  • the lithium ion batteries of Comparative Examples 1-2 and Examples 1-13 were all prepared according to the above preparation method.
  • the specific combinations and contents of lithium salts and additives are shown in Table 1.
  • Example 13 and Comparative Example 1 Based on the above Example 13 and Comparative Example 1, it can be seen that adding a nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group to the electrolyte can not only improve the high-temperature cycle performance, normal temperature cycle performance, rate performance and low-temperature discharge of the battery performance, and more importantly, can effectively avoid low-temperature lithium evolution. This is because there are lone electron pairs on the N atoms of nitrogen-containing heterocyclic compounds containing sulfonate groups or sulfone groups. Adding a small amount to the electrolyte can show weak Lewis basicity and can interact with other components in the electrolyte.
  • Components (such as PF 5 ) form complexes (such as six-ligand complexes) to reduce the acidity and reactivity of the electrolyte and inhibit the increase of free acid in the electrolyte; nitrogen-containing heterogeneous compounds containing sulfonate ester groups or sulfone groups
  • the cyclic compound can form an outer interface film containing a large amount of LiSO 3 , ROSO 2 Li, and Li x N y O z on the positive and negative electrodes during the first charge and discharge. It has good high temperature resistance and low impedance, which is conducive to the migration of lithium ions.
  • Fluorinated cyclic carbonate compounds form an interface film containing components such as LiF on the negative electrode, and are evenly dispersed on the surface of the negative electrode.
  • the interface film formed by the nitrogen-containing heterocyclic compound containing a sulfonate group or a sulfone group can inhibit lithium evolution and has high stability, and can be Improve cycle performance.
  • the fluorinated cyclic carbonate compounds can form an interface film rich in LiF on the negative electrode during the first charge and discharge stage. This interfacial film can significantly increase the number of lithium ions.
  • the penetration and diffusion capabilities at the negative electrode interface can increase the low temperature and rate performance of lithium-ion batteries.
  • the problem of lithium evolution cannot be solved when the electrolyte with a single addition of fluorinated cyclic carbonate compounds reaches a later stage of circulation or is circulated for a long time under low temperature conditions.
  • the positive electrode interface is in direct contact with the electrolyte to catalyze its decomposition, causing significant deterioration in normal and high temperature cycle performance.

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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，含磺酸酯基或砜基的含氮杂环类化合物为双功能添加剂，其N原子上存在孤电子对，少量添加到电解液中后即可呈现较弱的路易斯碱性，能与电解液中的其他组分(例如PF5)形成配合物(例如六配体的配合物)，降低电解液的酸性和反应活性，抑制电解液游离酸的升高；可以改善高电压电池的高温循环性能、常温循环性能、低温放电性能和倍率性能的同时抑制负极析锂。

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及含有该电解液的电池。
背景技术
二次电池具有比能量高、比功率大、循环寿命长、自放电小等显著优点，锂离子电池是一种常见的二次电池。商业用锂离子电池的正极材料主要有锰酸锂、钴酸锂、三元材料、磷酸亚铁锂几种，其充电截止电压一般不超过4.2V，随着科技的进步及市场的不断发展，提升锂离子电池的能量密度日益显得重要而迫切。
除了现有材料和电池的制作工艺改进之外，高电压(4.35V～5V)正极材料是比较热门的研究方向之一，它是通过提升正极活性材料的充电深度来实现电池的高能量密度。然而三元材料电池工作电压提高后，电池的充放电循环等性能却下降。其中，电解液作为锂离子电池的重要组成部分，对电池的充放电循环等性能有着重大的影响。电解液决定了锂离子(Li+)在液相中的迁移速率，同时还参与固体电解质界面(SEI)膜形成，对SEI膜性能起着关键性的作用，因此电解液在高压条件下可能导致锂离子电池的高温储存性能较差、高温循环性能较差、常温循环性能较差；同时低温下电解液的黏度增大，电导率降低，SEI膜阻抗增大，因此电解液还可能导致锂离子电池的低温放电性能较差，甚至产生低温析锂的风险。因此，亟需研发一种各方面性能优异的电解液以满足高能量密度三元材料电池的使用要求。
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。本公开通过在电解液中引入含磺酸酯基或砜基的含氮杂环类化合物，用于改善4.35V以上的高电压电池(特别是镍钴锰三元材料电池或镍钴铝三元材料电池)的高温循环性能、常温循环性能、低温放电性能和倍率性能的同时抑制负极析锂。
进一步地，通过在电解液中引入含磺酸酯基或砜基的含氮杂环类化合物和氟代环状碳酸酯类化合物的组合，能有效的避免电解液中单一氟代环状碳酸酯类化合物的进一步消耗以及电解液与负极界面之间的反应，从而进一步增强4.35V以上的高电压电池的高温循环性能、常温循环性能、低温放电性能和倍率性能的同时抑制负极析锂。
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，所述添加剂包括含磺酸酯基或砜基的含氮杂环类化合物。
根据本公开的实施方式，所述电解液用于镍钴锰三元材料电池或镍钴铝三元材料电池。
根据本公开的实施方式，所述含磺酸酯基或砜基的含氮杂环类化合物包括磺酸酯基或砜基，且磺酸酯基或砜基中的硫与氮形成杂环结构。
根据本公开的实施方式，所述电解液还包括氟代环状碳酸酯类化合物。
根据本公开的实施方式，所述氟代环状碳酸酯类化合物包括碳酸酯基，且碳酸酯基与烷基形成环状结构。
根据本公开的实施方式，所述含磺酸酯基或砜基的含氮杂环类化合物选自式1所示的化合物中的至少一种：
式1中，X为-O-或-N(R2)-；
R1为卤素、取代或未取代的烷基，若为取代时，取代基为卤素、烷基；
R2为取代或未取代的芳基、取代或未取代的烷基，若为取代时，取代基为卤素、烷基。
根据本公开的实施方式，R1为卤素、取代或未取代的C1-12烷基，若为取代时，取代基为卤素、C1-12烷基；
R2为取代或未取代的C6-20芳基、取代或未取代的C1-12烷基，若为取代时，取代基为卤素、C1-12烷基。
根据本公开的实施方式，R1为卤素、取代或未取代的C1-6烷基，若为取代时，取代基为卤素、C1-6烷基；
R2为取代或未取代的C6-10芳基、取代或未取代的C1-6烷基，若为取代时，取代基为卤素、C1-6烷基。
根据本公开的实施方式，R1为卤素、取代或未取代的C1-3烷基，若为取代时，取代基为卤素、C1-3烷基；
R2为取代或未取代的苯基、取代或未取代的C1-3烷基，若为取代时，取代基为卤素、C1-3烷基。
根据本公开的实施方式，所述含磺酸酯基或砜基的含氮杂环类化合物选自化合物A～化合物H中的至少一种：

根据本公开的实施方式，所述含磺酸酯基或砜基的含氮杂环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，所述含磺酸酯基或砜基的含氮杂环类化合物的质 量占电解液总质量的0.05wt％～1wt％，优选为0.1～0.5wt％，如0.05wt％、0.1wt％、0.2wt％、0.3wt％、0.4wt％、0.5wt％、0.6wt％、0.7wt％、0.8wt％、0.9wt％、1wt％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，所述氟代环状碳酸酯类化合物选自式2所示的化合物中的至少一种：
式2中，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的烷基，且至少含有一个F原子，若为取代时，取代基为F、烷基。
根据本公开的实施方案，式2中，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的C1-6烷基，且至少含有一个F原子，若为取代时，取代基为F、C1-6烷基。
根据本公开的实施方案，式2中，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的C1-3烷基，且至少含有一个F原子，若为取代时，取代基为F、C1-3烷基。
根据本公开的实施方式，所述氟代环状碳酸酯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，所述氟代环状碳酸酯类化合物的质量占电解液总质量的0.5wt％～12wt％，优选为1wt％～10wt％，例如为0.5wt％、1wt％、2wt％、3wt％、4wt％、5wt％、6wt％、7wt％、8wt％、9wt％、10wt％、11wt％、12wt％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，所述氟代环状碳酸酯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等中的至少一种。
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电解液总质量的13～20wt％，例如13wt％、14wt％、15wt％、16wt％、17wt％、18wt％、19wt％或20wt％。
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，所述电池包括上述的电解液。
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，所述电池为镍钴锰三元电池或镍钴铝三元电池。
根据本公开的实施方式，所述电池还包括含有正极活性材料的正极片、含有负极活性材料的负极片、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正极活性物质、导电剂和粘结剂。
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负极活性材料、导电剂和粘结剂。
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％的正极活性材料、0.1wt％～10wt％的导电剂、0.1wt％～10wt％的粘结剂。
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％的正极活性物质、0.2wt％～5wt％的导电剂、0.2wt％～5wt％的粘结剂。
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％的负极活性物质、0.1wt％～10wt％的导电剂、0.1wt％～10wt％的粘结剂。
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％的负极活性物质、0.2wt％～5wt％的导电剂、0.2wt％～5wt％的粘结剂。
根据本公开的实施方式，所述导电剂选自导电炭黑、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，所述粘结剂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≤1，0<z≤1，x+y+z≤1。
根据本公开的实施方式，所述负极活性材料选自人造石墨、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4.35V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，含磺酸酯基或砜基的含氮杂环类化合物为双功能添加剂，其N原子上存在孤电子对，少量添加到电解液中后即可呈现较弱的路易斯碱性，能与电解液中的其他组分(例如PF5，五氟化磷)形成配合物(例如六配体的配合物)，降低电解液的酸性和反应活性，抑制电解液游离酸的升高；同时，含磺酸酯基或砜基的含氮杂环类化合物在首次充放电时能够在正负极形成含有大量LiSO3、ROSO2Li、LixNyOz(0＜x≤3，0＜y≤1，2＜z≤3)的外层界面膜，耐高温性能好，阻抗低，有利于锂离子的迁移，可以改善高电压电池的高温循环性能、常温循环性能、低温放电性能和倍率性能的同时抑制负极析锂。
在此基础上，当电解液同时加入含磺酸酯基或砜基的含氮杂环类化合物和氟代环状碳酸酯类化合物时，二者之间产生协同增效的作用，二者共同作用于正负极表面，能够进一步增强高电压电池的高温循环性能、常温循环性能、低温放电性能和倍率性能的同时抑制负极析锂，可以有效的避免电解液中单一氟代环状碳酸酯类化合物的进一步消耗以及电解液与负极界面之间的反应。
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
将正极活性材料镍钴锰酸锂三元材料LiNi0.6Mn0.2Co0.2O2(NCM622)、粘结剂聚偏氟乙烯(PVDF)、导电剂乙炔黑按照重量比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
将负极活性材料人造石墨、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、导电剂单壁碳纳米管(SWCNT)按照重量比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)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)以25:5:60:10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、负极片通过卷绕得到未注液的裸电芯；将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1-13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1-13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1-13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4.35V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，按照计算公式：容量保持率(％)＝Q1/Q×100％，将计算后的容量保持率的结果记录于表2中。
(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4.35V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，按照计算公式：容量保持率(％)＝Q1/Q×100％，将计算后的容量保持率的结果记录于表2中。
(3)-10℃低温放电实验：在25℃下，将锂离子电池以0.5C恒流放电至截至电压3V，搁置10min后，以1C恒流恒压充电至4.35V截止电流0.05C，电芯移至-10℃低温箱中，搁置120min后，以4C恒流放电至截至电压3.0V，记录拐点电压，记录结果如表2。
(4)-10℃循环解剖实验：将上述实施例和对比例所得电池置于(-10±2)℃环境中，静置2-3小时，待电池本体达到(-10±2)℃时，电池按照1C恒流恒压充电至4.35V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，重复上述工步循环10周，解剖记录结果如表2。
(5)60℃高温存储30天酸度变化实验：将上述实施例和对比例所制备的电解液测试存储前酸度，再置于60±2℃恒温箱中存储30天后测试酸度，记录结果如表2。
表2对比例1-2及实施例1-13的锂离子电池和电解液的性能测试结果

综合上述实施例13和对比例1可知，将含磺酸酯基或砜基的含氮杂环类化合物添加到电解液中不仅可以提高电池的高温循环性能、常温循环性能、倍率性能和低温放电性能，更重要的是能有效避免低温析锂。这是由于含磺酸酯基或砜基的含氮杂环类化合物的N原子上存在孤电子对，少量添加到电解液中即可呈现较弱的路易斯碱性，能与电解液中的其他组分(例如PF5)形成配合物(例如六配体的配合物)，降低电解液的酸性和反应活性，抑制电解液游离酸的升高；含磺酸酯基或砜基的含氮杂环类化合物在首次充放电时能够在正负极形成含有大量LiSO3、ROSO2Li、LixNyOz的外层界面膜，耐高温性能好，阻抗低，有利于锂离子的迁移，氟代环状碳酸酯类化合物在负极形成含有LiF等成分的界面膜，并均匀分散在负极表面。
进一步地，上述实施例1～13和对比例1～2可知，含磺酸酯基或砜基的含氮杂环类化合物形成的界面膜能抑制析锂且稳定性高，且能于一定程度上改善循环性能。在此基础上，进一步加入氟代环状碳酸酯类化合物后，氟代环状碳酸酯类化合物可在首次充放电阶段于负极形成富含LiF的界面膜，该层界面膜能明显增加锂离子在负极界面的穿透与扩散能力，故而能增加锂离子电池的低温与倍率性能。
而单一加入氟代环状碳酸酯类化合物的电解液在循环到后期或在低温条件下长循环后，其析锂问题无法得到解决。另外，由于没有添加含磺酸酯基或砜基的含氮杂环类化合物，正极界面与电解液直接接触催化其分解，造成常温和高温循环性能明显劣化。
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，所述添加剂包括含磺酸酯基或砜基的含氮杂环类化合物。
  2. 根据权利要求1所述的电解液，其特征在于，所述含磺酸酯基或砜基的含氮杂环类化合物包括磺酸酯基或砜基，且磺酸酯基或砜基中的硫与氮形成杂环结构。
  3. 根据权利要求1或2所述的电解液，其特征在于，所述含磺酸酯基或砜基的含氮杂环类化合物选自式1所示的化合物中的至少一种：
    式1中，X为-O-或-N(R2)-；
    R1为卤素、取代或未取代的烷基，若为取代时，取代基为卤素、烷基；
    R2为取代或未取代的芳基、取代或未取代的烷基，若为取代时，取代基为卤素、烷基。
  4. 根据权利要求3所述的电解液，其特征在于，式1中，R1为卤素、取代或未取代的C1-12烷基，若为取代时，取代基为卤素、C1-12烷基；
    R2为取代或未取代的C6-20芳基、取代或未取代的C1-12烷基，若为取代时，取代基为卤素、C1-12烷基。
  5. 根据权利要求4所述的电解液，其特征在于，式1中，R1为卤素、取代或未取代的C1-3烷基，若为取代时，取代基为卤素、C1-3烷基；
    R2为取代或未取代的苯基、取代或未取代的C1-3烷基，若为取代时，取代基为卤素、C1-3烷基。
  6. 根据权利要求1-5任一项所述的电解液，其特征在于，所述含磺酸酯基或砜基的含氮杂环类化合物选自化合物A～化合物H中的至少一种：

  7. 根据权利要求1-6任一项所述的电解液，其特征在于，所述含磺酸酯基或砜基的含氮杂环类化合物的质量占电解液总质量的0.05wt％～1wt％，优选为0.1wt％～0.5wt％。
  8. 根据权利要求1-7任一项所述的电解液，其特征在于，所述电解液还包括氟代环状碳酸酯类化合物；
    优选地，所述氟代环状碳酸酯类化合物包括碳酸酯基，且碳酸酯基与烷基形成环状结构。
  9. 根据权利要求8所述的电解液，其特征在于，所述氟代环状碳酸酯类化合物选自式2所示的化合物中的至少一种：
    式2中，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的烷基，且至少含有一个F原子，若为取代时，取代基为F、烷基。
  10. 根据权利要求9所述的电解液，其特征在于，式2中，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的C1-6烷基，且至少含有一个F原子，若为取代时，取代基为F、C1-6烷基；
    优选地，R3和R4相同或不同，彼此独立地选自H、F、取代或未取代的C1-3烷基，且至少含有一个F原子，若为取代时，取代基为F、C1-3烷基。
  11. 根据权利要求8-10任一项所述的电解液，其特征在于，所述氟代环状碳酸酯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8-11所述的电解液，其特征在于，所述氟代环状碳酸酯类化合物的质量占电解液总质量的0.5wt％～12wt％，优选为1wt％～10wt％。
  13. 根据权利要求1-12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，所述电解质盐的质量占电解液总质量的13wt％～20wt％。
  14. 一种电池，其特征在于，所述电池包括权利要求1-13任一项所述的电解液。
  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≤1，0<z≤1，x+y+z≤1。
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