WO2023123841A1 - 电解液添加剂和含有该添加剂的电解液及锂离子电池 - Google Patents

电解液添加剂和含有该添加剂的电解液及锂离子电池 Download PDF

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WO2023123841A1
WO2023123841A1 PCT/CN2022/095091 CN2022095091W WO2023123841A1 WO 2023123841 A1 WO2023123841 A1 WO 2023123841A1 CN 2022095091 W CN2022095091 W CN 2022095091W WO 2023123841 A1 WO2023123841 A1 WO 2023123841A1
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lithium
electrolyte
additive
ion battery
formula
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English (en)
French (fr)
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欧霜辉
王霹霹
白晶
毛冲
黄秋洁
戴晓兵
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珠海市赛纬电子材料股份有限公司
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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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • 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

Definitions

  • the application belongs to the technical field of lithium-ion batteries, and in particular relates to an electrolyte additive, an electrolyte containing the additive, and a lithium-ion battery.
  • Lithium-ion batteries Due to its high energy density, low self-discharge, excellent cycle stability and no memory effect, lithium-ion batteries have become a vital part of the power battery field in the current new energy vehicle industry.
  • Lithium-ion batteries are mainly composed of positive electrode materials, negative electrode materials, separators and electrolytes; among them, nickel-cobalt-manganese ternary positive electrode materials (NCM materials) have become the first choice for positive electrode active materials of lithium-ion batteries due to their good safety and low price.
  • NCM materials nickel-cobalt-manganese ternary positive electrode materials
  • ternary cathode materials are developing in the direction of high nickel (Ni ⁇ 0.6), the specific capacity of the material will increase significantly, but the mixing effect of lithium-nickel cations is enhanced, and the cycle of the material is stable sex decline.
  • the market has put forward higher requirements for the energy density of ternary cathode materials with high nickel (Ni ⁇ 0.6) in the positive direction. It is a feasible method to increase the cut-off voltage of cathode materials; however, with the increase of cut-off voltage, side reactions will occur.
  • the cycle stability of the material drops sharply; and a large number of studies have shown that the main reason for the poor cycle performance of the material is that the particle morphology of the ternary cathode material is mostly spherical secondary particles, which are formed by the agglomeration of primary particles , during the electrochemical cycle of this type of material, due to the phenomenon of uneven charge distribution among the primary particles, each primary particle will generate different stresses, and the degree of volume shrinkage/expansion is inconsistent, so after the cycle, the primary Cracks are generated between the particles, and the generation of cracks will cause the electrolyte to enter the cracks and increase the reaction area; the electrochemical cycle continues, and as the number of cycles increases, the cracks continue to expand, and even run through the entire secondary particle, resulting in secondary Particles break or even break, deteriorating battery performance.
  • the purpose of this application is to provide an electrolyte additive, which is easy to form a tough interfacial film at the electrolyte interface, alleviates the damage of the material crack stress to the electrode electrolyte interface, and improves the cycle performance and storage performance of lithium-ion batteries .
  • Another object of the present application is to provide an electrolyte containing the above-mentioned additives, which can easily form a tough interface film at the interface of the electrolyte, alleviate the damage of the crack stress of the material to the electrolyte interface of the electrode, and improve the cycle of the lithium-ion battery. performance and storage performance.
  • Another object of the present application is to provide a lithium-ion battery containing the above electrolyte, which has good cycle performance and good storage performance.
  • an electrolyte additive including at least one of formula 1 and formula 2:
  • R 1 ⁇ R 10 are each independently selected from hydrogen, halogen, substituted or unsubstituted C1 ⁇ C6 alkyl, substituted or unsubstituted C2 ⁇ C6 alkenyl, substituted or unsubstituted C2 ⁇ C6 alkynyl;
  • X, Y is each independently selected from any of silicon, sulfur, phosphorus, nitrogen, oxygen, and carbon;
  • n, m, q, and s are each independently selected from any of 0 and 1.
  • the compounds shown in formula 1 and formula 2 of the present application are all composed of two five-membered alkene ring structures directly connected, and the structure is relatively stable, and it is easy to form a tough interfacial film at the electrode electrolyte interface to alleviate
  • the damage of material crack stress to the electrolyte interface of the electrode improves the cycle performance and storage performance of lithium-ion batteries; the interface film also has good conduction lithium ion channels, which will not cause the collapse of lithium ion channels during cycling, thereby further improving cycle performance.
  • X and Y are independently selected from any one of silicon, sulfur, phosphorus, nitrogen, oxygen, and carbon, which enriches the electrode/electrolyte interface film components and further improves the thermal stability of the interface film, thereby further improving storage performance of lithium-ion batteries. Therefore, the application of the electrolyte additive to the lithium ion battery can improve the cycle performance and storage performance of the lithium ion battery.
  • R 1 to R 10 in the present application are all hydrogen.
  • X and Y in the present application are different, which can form an interface component with more abundant elements, which helps to improve the structural stability of the interface film and improve the cycle performance and storage performance of lithium-ion batteries.
  • the CAS number of the compound represented by Formula 2 of the present application is: 723302-68-9.
  • the compound shown in formula 1 of the present application is selected from at least one of compound 1 ⁇ compound 5:
  • the present application also provides an electrolyte, including a lithium salt, an organic solvent and an additive, and the additive includes the above electrolyte additive.
  • the electrolyte solution of the present application includes the compounds shown in formula 1 and formula 2, and the application of the electrolyte solution to lithium ion batteries can improve the cycle performance and storage performance of lithium ion batteries.
  • the mass of the electrolyte additive of the present application accounts for 0.1-5.0% of the sum of the mass of the lithium salt and the organic solvent.
  • the lithium salt of the present application is lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bisfluorosulfonimide (LiFSI), lithium tetrafluoroborate (LiBF 4 ), trifluoromethanesulfonic acid Lithium (LiCF 3 SO 3 ), lithium difluorooxalate borate (C 2 BF 2 LiO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium difluorobisoxalate phosphate (LiDFBP), lithium methanesulfonate (LiCH 3 SO 3 ), At least one of lithium perchlorate (LiClO 4 ), lithium dioxalate borate (C 4 BLiO 8 ), and lithium difluorophosphate (LiPO 2 F 2 ), the concentration of the lithium salt in the electrolyte is 0.5-1.5M.
  • LiTFSI lithium bistrifluoromethanesulfonimide
  • the organic solvent in the present application is at least one selected from chain carbonates, carboxylates, ethers and heterocyclic compounds.
  • the additive of the present application also includes a film-forming additive, and the film-forming additive is selected from fluoroethylene carbonate (FEC), vinyl sulfite (ES), 1,3 propane sultone (PS) and vinyl sulfate At least one of ester (DTD), vinylene carbonate (VC) and vinylene ethylene carbonate (VEC).
  • FEC fluoroethylene carbonate
  • ES vinyl sulfite
  • PS 1,3 propane sultone
  • VEC vinyl sulfate
  • the film-forming additive accounts for 0.1-6.0% of the total mass of the lithium salt and the organic solvent, and the film-forming additive can further improve the cycle performance and storage performance of the lithium-ion battery.
  • the present application also provides a lithium-ion battery, including a positive electrode and a negative electrode, and also includes the above-mentioned electrolyte, and the highest charging voltage is 4.4V, and the active material of the positive electrode includes nickel-cobalt-manganese oxide material.
  • the electrolyte of the lithium-ion battery of the present application includes compounds shown in formula 1 or formula 2, which are all composed of two five-membered olefinic ring structures directly connected to each other.
  • the structure is relatively stable, and it is easy to dissolve in the electrolyte
  • the interface forms a relatively tough interface film, which relieves the damage of the material crack stress to the electrode electrolyte interface, and improves the cycle performance and storage performance of the lithium-ion battery;
  • the collapse of lithium-ion channels further improves the cycle performance of lithium-ion batteries.
  • X and Y are independently selected from any one of silicon, sulfur, phosphorus, nitrogen, oxygen, and carbon, which enriches the electrode/electrolyte interface film components and further improves the thermal stability of the interface film, thereby further improving
  • the storage performance of lithium-ion batteries in high-voltage (4.4V and above) systems was tested.
  • the chemical formula of the nickel-cobalt-manganese oxide material of the present application is LiNi x Co y Mn( 1-xy )M z O 2 , where 0.6 ⁇ x ⁇ 0.9, x+y ⁇ 1, 0 ⁇ z ⁇ 0.08, M is at least one of Al, Mg, Zr and Ti.
  • the anode of the present application is a carbon anode material, a silicon anode material or a silicon-carbon anode material.
  • LiPF 6 lithium hexafluorophosphate
  • VC vinylene carbonate
  • FEC additive fluoroethylene carbonate
  • LiNi 6 Co 2 Mn 2 Zr 0.3 O 2 ternary material LiNi 6 Co 2 Mn 2 Zr 0.3 O 2 , conductive agent SuperP, binder PVDF and carbon nanotube (CNT) were uniformly mixed at a mass ratio of 97.5:1.5:1:1 to make a certain Viscosity lithium-ion battery positive electrode slurry is coated on the aluminum foil for the current collector, and the coating amount is 324g/m 2 , dried at 85°C and then cold-pressed; then edge trimming, cutting, and slitting After slitting, dry at 85°C for 4 hours under vacuum conditions, and weld the tabs to make a lithium-ion battery positive sheet that meets the requirements.
  • Preparation of the negative electrode sheet After mixing artificial graphite and silicon in a mass ratio of 90:10, with a conductive agent SuperP, a thickener CMC, and an adhesive SBR (styrene-butadiene rubber emulsion) in a mass ratio of 95:1.5:1.0: The ratio of 2.5 is made into a slurry, mixed evenly, coated on both sides of the copper foil with the mixed slurry, dried and rolled to obtain a negative electrode sheet, and made into a lithium ion battery negative electrode sheet that meets the requirements.
  • a conductive agent SuperP a conductive agent
  • CMC thickener
  • an adhesive SBR styrene-butadiene rubber emulsion
  • lithium-ion battery The positive electrode sheet, negative electrode sheet and diaphragm prepared according to the above process are laminated into a lithium-ion battery with a thickness of 4.7mm, a width of 55mm, and a length of 60mm, and vacuum-dry at 75°C Bake for 10 hours and inject the above electrolyte.
  • Example 2-9 and Comparative Examples 1-4 The components of the electrolyte solutions of Examples 2-9 and Comparative Examples 1-4 are shown in Table 1, and the preparation methods of the electrolyte solutions of Examples 2-9 and Comparative Examples 1-4 refer to the preparation method of Example 1.
  • Example 2 Using the electrolytes of Examples 2 to 9 and Comparative Examples 1 to 4, a lithium ion battery was manufactured with reference to the lithium ion battery preparation method of Example 1, and the normal temperature cycle performance and high temperature cycle performance of the lithium ion battery were respectively tested according to the following test methods. Performance and high-temperature storage performance tests, the test results are shown in Table 2.
  • the electrical properties of the lithium-ion batteries of Examples 1-9 are all better than those of Comparative Examples 1-4, which shows that the structures of the compounds shown in Structural Formula 1 and Formula 2 are relatively stable, and are easy to form at the electrode electrolyte interface.
  • the tough interface film can alleviate the damage of the material crack stress to the electrode electrolyte interface, and improve the cycle performance and storage performance of lithium-ion batteries; the interface film also has good conduction lithium ion channels, which will not generate lithium ion channels during cycling collapse, thereby further improving cycle performance.
  • X and Y are independently selected from any one of silicon, sulfur, phosphorus, and nitrogen, which enriches the electrode/electrolyte interface film components and further improves the thermal stability of the interface film, thereby further improving the lithium-ion battery. storage performance.
  • Comparative Example 3 contains thiophene groups and pyrrole groups, the electrical performance of the lithium-ion battery of Comparative Example 3 is still worse than that of Example 4, because the oxidation and reduction potentials of thiophene and pyrrole are different.

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Abstract

一种电解液添加剂和含有该添加剂的电解液及锂离子电池，其中电解液添加剂包括式1和式2中的至少一种：其中，R 1～R 10各自独立地选自氢、卤素、取代或未取代的C1～C6烷基、取代或未取代的C2～C6烯基、取代或未取代的C2～C6炔基；X、Y各自独立地选自硅、硫、磷、氮、氧、碳中的任一种；n、m、q、s各自独立地选自0、1中的任一种。该电解液添加剂容易在电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的循环性能和存储性能。

Description

电解液添加剂和含有该添加剂的电解液及锂离子电池 技术领域
本申请属于锂离子电池技术领域，尤其涉及一种电解液添加剂和含有该添加剂的电解液及锂离子电池。
背景技术
锂离子电池因其具有能量密度高、自放电小、循环稳定性能优异以及无记忆效应等特点，使其成为了当下新能源汽车产业中的动力电池领域至关重要的一部分。锂离子电池主要由正极材料、负极材料、隔膜和电解液构成；其中，镍钴锰三元正极材料(NCM材料)由于安全性好以及价格低廉，成为锂离子电池的正极活性材料的首选材料。
为了满足了市场对正极材料能量密度的需求，三元正极材料正向高镍(Ni≥0.6)方向发展，材料的比容量会显著升高，但锂镍阳离子混排效应增强，材料的循环稳定性下降。目前市场对于三元正极材料正向高镍(Ni≥0.6)的能量密度提出了更高的要求，提高正极材料的截至电压是一种可行的方法；但是随着截至电压的提高，副反应会随之加剧，材料的循环稳定性能急剧下降；而大量研究表明材料循环性能较差的主要原因为：三元正极材料的颗粒形貌多为类球形的二次颗粒，是由一次颗粒团聚而成，这种类型的材料在电化学循环过程中，由于一次颗粒之间存在电荷分布不均匀的现象，因此每个一次颗粒会产生不同的应力，体积收缩/膨胀程度不一致，因此通过循环后，一次颗粒之间产生裂纹，而裂纹的生成，会使电解液进入裂缝中，反应面积增加；继续进行电化学循环，随着循环次数的增加，裂纹不断扩大，甚至贯穿整个二次颗粒，导致二次颗粒断裂甚至破碎，劣化电池性能。
因此，亟需一种电解液添加剂和含有该添加剂的电解液及锂离子电池，以 解决现有技术问题的不足。
申请内容
本申请的目的是提供一种电解液添加剂，该电解液添加剂容易在电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的循环性能和存储性能。
本申请的又一目的是提供一种含有上述添加剂的电解液，该电解液容易在电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的循环性能和存储性能。
本申请的另一目的是提供一种含有上述电解液的锂离子电池，该锂离子电池具有良好的循环性能和良好的存储性能。
为实现以上目的，本申请提供了一种电解液添加剂，包括式1和式2中的至少一种：
Figure PCTCN2022095091-appb-000001
其中，R 1～R 10各自独立地选氢、卤素、取代或未取代的C1～C6烷基、取代或未取代的C2～C6烯基、取代或未取代的C2～C6炔基；X、Y各自独立地选自硅、硫、磷、氮、氧、碳中的任一种；n、m、q、s各自独立地选自0、1中的任一种。
与现有技术相比，本申请的式1、式2所示的化合物皆由两个五元烯环结构直接相连构成，结构较稳定，容易在电极电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的循环性能和存储性能；该界面膜还具有良好的传导锂离子通道，不致于在循环过程中产生锂离子通道的坍塌，从而进一步改善循环性能。同时X、Y各自独立地选自硅、硫、 磷、氮、氧、碳中的任一种，丰富了电极/电解液界面膜组分，进一步改善了界面膜的热稳定性，从而进一步改善了锂离子电池的存储性能。因此将该电解液添加剂应用于锂离子电池，可改善锂离子电池的循环性能和存储性能。
较佳地，本申请的R 1～R 10皆为氢。
较佳地，本申请的X与Y不相同，可以形成元素更为丰富的界面组分，有助于提高界面膜的结构稳定性，改善锂离子电池的循环性能及存储性能。
具体地，本申请的式2所示的化合物的CAS号为:723302-68-9。
较佳地，本申请的式1所示的化合物选自化合物1～化合物5中的至少一种:
Figure PCTCN2022095091-appb-000002
为实现以上目的，本申请还提供了一种电解液，包括锂盐、有机溶剂和添加剂，添加剂包括上述的电解液添加剂。
与现有技术相比，本申请的电解液包括式1、式2所示的化合物，将该电解液应用于锂离子电池，可改善锂离子电池的循环性能和存储性能。
较佳地，本申请的电解液添加剂的质量占锂盐和有机溶剂质量之和的0.1～5.0％。
较佳地，本申请的锂盐为双三氟甲基磺酰亚胺锂(LiTFSI)、双氟磺酰亚胺锂(LiFSI)、四氟硼酸锂(LiBF 4)、三氟甲基磺酸锂(LiCF 3SO 3)、二氟草酸硼酸锂(C 2BF 2LiO 4)、六氟磷酸锂(LiPF 6)、二氟双草酸磷酸锂(LiDFBP)、甲基磺酸锂(LiCH 3SO 3)、高氯酸锂(LiClO 4)、二草酸硼酸锂(C 4BLiO 8)、二氟磷酸锂(LiPO 2F 2)中的至少一种，锂盐于电解液中的浓度为0.5～1.5M。
较佳地，本申请的有机溶剂选自链状碳酸酯类、羧酸酯类、醚类和杂环化合物的至少一种。
较佳地，本申请的添加剂还包括成膜添加剂，成膜添加剂选自氟代碳酸乙烯酯(FEC)、亚硫酸乙烯酯(ES)、1,3丙磺酸内酯(PS)和硫酸乙烯酯(DTD)、碳酸亚乙烯酯(VC)和亚乙烯基碳酸乙烯酯(VEC)中的至少一种。成膜添加剂占锂盐和有机溶剂质量之和的0.1～6.0％，成膜添加剂能够进一步地改善锂离子电池的循环性能和存储性能。
为实现以上目的，本申请还提供了一种锂离子电池，包括正极和负极，还包括上述的电解液，且最高充电电压为4.4V，正极的活性材料包括镍钴锰氧化物材料。
与现有技术相比，本申请的锂离子电池的电解液中包括式1或式2所示的化合物，其皆由两个五元烯环结构直接相连构成，结构较稳定，容易在电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的循环性能和存储性能；该界面膜还具有良好的传导锂离子通道，不致于在循环过程中产生锂离子通道的坍塌，从而进一步改善锂离子电池的循环性能。同时X、Y各自独立地选自硅、硫、磷、氮、氧、碳中的任一种，丰富了电极/电解液界面膜组分，进一步改善了界面膜的热稳定性，从而进一步改善了锂离子电池于高电压(4.4V及以上)体系下的存储性能。
较佳地，本申请的镍钴锰氧化物材料的化学式为LiNi xCo yMn( 1-x-y)M zO 2，其中0.6≤x<0.9，x+y<1，0≤z<0.08，M为Al、Mg、Zr和Ti中的至少一种。优选地，采用x＝0.6，y＝0.2，M为Zr，z＝0.03。
较佳地，本申请的负极为碳负极材料、硅负极材料或硅碳负极材料。
具体实施方式
为更好地说明本申请的目的、技术方案和有益效果，下面将结合具体实施例对本申请作进一步说明。需说明的是，下述实施所述方法是对本申请做的进一步解释说明，不应当作为对本申请的限制。
实施例1
1、电解液的制备
将碳酸乙烯酯(EC)、碳酸二乙酯(DEC)和碳酸甲乙酯(EMC)按质量 比为EC:DEC:EMC＝29.16:29.16:29.16进行混合，制得87.48g有机溶剂，混合后加入1M的六氟磷酸锂(LiPF 6)，待锂盐完全溶解后，再加入1g的碳酸亚乙烯酯(VC)和5g的添加剂氟代碳酸乙烯酯(FEC)及0.5g的化合物1。
2、正极片的制备
将镍钴锰酸锂三元材料LiNi 6Co 2Mn 2Zr 0.3O 2、导电剂SuperP、粘接剂PVDF和碳纳米管(CNT)按质量比97.5:1.5:1:1混合均匀制成一定粘度的锂离子电池正极浆料，涂布在集流体用铝箔上，其涂布量为324g/m 2，在85℃下烘干后进行冷压；然后进行切边、裁片、分条，分条后在真空条件下85℃烘干4小时，焊接极耳，制成满足要求的锂离子电池正极片。
3、负极片的制备：将人造石墨，硅按质量比90:10混合后，与导电剂SuperP、增稠剂CMC、粘接剂SBR(丁苯橡胶乳液)按质量比95:1.5:1.0:2.5的比例制成浆料，混合均匀，用混制的浆料涂布在铜箔的两面后，烘干、辊压后得到负极片，制成满足要求的锂离子电池负极片。
4、锂离子电池的制备：将根据上述工艺制备的正极片、负极片和隔膜经叠片工艺制作成厚度为4.7mm，宽度为55mm，长度为60mm的锂离子电池，在75℃下真空烘烤10小时，注入上述电解液。静置24小时后，用0.lC(180mA)的恒流充电至4.4V，然后以4.4V恒压充电至电流下降到0.05C(90mA)；然后以0.2C(180mA)放电至3.0V，重复2次充放电，最后再以0.2C(180mA)将电池充电至3.8V，完成锂离子电池制作。
实施例2～9和对比例1～4的电解液组成成分如表1所示，实施例2～9和对比例1～4的电解液配制方法参照实施例1的配制方法进行。
表1实施例和对比例的电解液组成成分
Figure PCTCN2022095091-appb-000003
Figure PCTCN2022095091-appb-000004
上述化合物6、7、8的结构式如下所述：
Figure PCTCN2022095091-appb-000005
以实施例2～9和对比例1～4的电解液，参照实施例1的锂离子电池制备方法制成锂离子电池，并按照下述测试方法分别对锂离子电池的常温循环性能、高温循环性能、高温存储性能测试，测试结果如表2所示。
常温循环性能测试：
在常温(25℃)条件下，对锂离子电池进行一次1.0C/1.0C充电和放电(电池放电容量为C0)，上限电压为4.4V，然后在常温条件下进行1.0C/1.0C充电和放电500周(电池放电容量为C1)，
容量保持率＝(C1/C0)*100％
高温循环性能测试：
在过高温(45℃)条件下，对锂离子电池进行一次1.0C/1.0C充电和放电(电池放电容量为C0)，上限电压为4.4V，然后在常温条件下进行1.0C/1.0C充电和放电500周(电池放电容量为C1)，
容量保持率＝(C1/C0)*100％
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4.4V；将电池放置于60℃烘箱中搁置15d，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)，
容量保持率＝(C1/C0)*100％
容量恢复率＝(C2/C0)*100％
表2锂离子电池的性能测试结果
Figure PCTCN2022095091-appb-000006
从表2可知，实施例1～9的锂离子电池的电性能皆优于对比例1～4，这表明结构式1、式2所示的化合物的结构较稳定，容易在电极电解液界面形成较为坚韧的界面膜，缓解材料裂纹应力对电极电解液界面的破坏，改善锂离子电池的 循环性能和存储性能；该界面膜还具有良好的传导锂离子通道，不致于在循环过程中产生锂离子通道的坍塌，从而进一步改善循环性能。同时X、Y各自独立地选自硅、硫、磷、氮中的任一种，丰富了电极/电解液界面膜组分，进一步改善了界面膜的热稳定性，从而进一步改善了锂离子电池的存储性能。
从表2可知，实施例5、实施例9的锂离子电池的性能比实施例2～4、实施例6略差，这表明X与Y不相同，可以形成元素更为丰富的界面组分，有助于提高界面膜的结构稳定性，改善锂离子电池的循环性能及存储性能。
从表2可知，虽然对比例3中含有噻吩基团和吡咯基团，但是对比例3的锂离子电池的电性能仍比实施例4差，这是因为噻吩和吡咯的氧化和还原电位均不同,会导致成膜紊乱，故于高电压下并不能在电极电解液界面形成较为坚韧的界面膜，进而也不能改善锂离子电池的循环性能及存储性能；同时虽然对比例4中将化合物8的浓度增大一倍，即将环戊二烯基团的浓度保持和实施例5相同，但是锂离子电池的电性能仍比实施例5差；因此，从对比例3和实施例4相比较的结果及对比例4和实施例5相比较的结果可知表明结构式1所示的化合物是作为一个化合物整体发挥作用的，从而有效改善高电压三元锂离子电池的电化学性能。
最后应当说明的是，以上实施例仅用以说明本申请的技术方案而非对本申请保护范围的限制，尽管参照较佳实施例对本申请作了详细说明，本领域的普通技术人员应当理解，可以对本申请的技术方案进行修改或者等同替换，而不脱离本申请技术方案的实质和范围。

Claims (10)

  1. 一种电解液添加剂，其特征在于，包括式1和式2中的至少一种：
    Figure PCTCN2022095091-appb-100001
    其中，R 1～R 10各自独立地选氢、卤素、取代或未取代的C1～C6烷基、取代或未取代的C2～C6烯基、取代或未取代的C2～C6炔基；X、Y各自独立地选自硅、硫、磷、氮、氧、碳中的任一种；n、m、q、s各自独立地选自0、1中的任一种。
  2. 如权利要求1所述的电解液添加剂，其特征在于，R 1～R 10皆为氢。
  3. 如权利要求2所述的电解液添加剂，其特征在于，X与Y不相同。
  4. 如权利要求1所述的电解液添加剂，其特征在于，所述式1所示的化合物选自化合物1～化合物5中的至少一种:
    Figure PCTCN2022095091-appb-100002
  5. 一种电解液，包括锂盐、有机溶剂和添加剂，其特征在于，所述添加剂包括如 权利要求1～4任一项所述的电解液添加剂。
  6. 如权利要求5所述的电解液，其特征在于，所述电解液添加剂的质量占所述锂盐和所述有机溶剂质量之和的0.1～5.0％。
  7. 如权利要求5所述的电解液，其特征在于，所述锂盐为双三氟甲基磺酰亚胺锂、双氟磺酰亚胺锂、四氟硼酸锂、三氟甲基磺酸锂、二氟草酸硼酸锂、六氟磷酸锂、二氟双草酸磷酸锂、甲基磺酸锂、高氯酸锂、二草酸硼酸锂、二氟磷酸锂中的至少一种，所述锂盐于所述电解液中的浓度为0.5～1.5M。
  8. 如权利要求5所述的电解液，其特征在于，所述有机溶剂选自链状碳酸酯类、羧酸酯类、醚类和杂环化合物的至少一种。
  9. 一种锂离子电池，包括正极和负极，其特征在于，还包括如权利要求5～8任一项所述的电解液，且最高充电电压为4.4V，所述正极的活性材料包括镍钴锰氧化物材料。
  10. 如权利要求9所述的锂离子电池，其特征在于，所述镍钴锰氧化物材料的化学式为LiNi xCo yMn( 1-x-y)M zO 2，其中0.6≤x<0.9，x+y<1，0≤z<0.08，M为Al、Mg、Zr和Ti中的至少一种。
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