调控电解液溶剂组分实现LCO/C低温18650电池循环寿命显著提升  

Controlling electrolyte solvent components to enhance cycle life of LCO/C low-temperature 18650 batteries

作　　者：程广玉[1] 刘新伟 刘硕 顾海涛[1] 王可[1] CHENG Guangyu;LIU Xinwei;LIU Shuo;GU Haitao;WANG Ke(State Key Laboratory of Space Power Sources,Shanghai Institute of Space Power-Sources,Shanghai 200245,China;Shanghai Aerospace Power Technology Co.Ltd.,Shanghai 201112,China)

机构地区：[1]空间电源全国重点实验室,上海空间电源研究所,上海200245 [2]上海航天电源技术有限责任公司,上海201112

出　　处：《储能科学与技术》2024年第7期2171-2180,共10页Energy Storage Science and Technology

基　　金：国家重点研发计划项目(2022YFB3803400);2023年上海市促进文化创意产业发展财政扶持资金项目(2023010560)。

摘　　要：低温18650电池的循环寿命一直是限制其发展的关键因素,为了实现长循环寿命与低温性能的兼顾,通过调控电解液溶剂组分,对比分析了不同电解液对电池倍率性能、高低温放电、荷电保持率、循环寿命、EIS阻抗变化等的影响。结果表明,电解液组分设计对电池性能有显著影响,通过低熔点的长链线性羧酸酯部分取代碳酸酯及短链羧酸酯,既可以实现较好的低温性能,同时又提升了高温稳定性。EP、PP的比例对于LCO/C电极体系循环稳定性有重要作用。其中溶剂组分EC+EP+PP(质量比2∶5∶3)具备最佳的综合性能,研制的LTB电池5C放电容量保持率达99.86%,-40℃/1C放电容量保持率达92.84%,循环1000次后低温-40℃/1C放电仍然达到初始低温放电容量的90%,常温循环1500次容量保持率达85%,低温-10℃循环500次容量保持率82.4%。The cycle life of low-temperature 18650 batteries has always been a key factor that limited their development.To achieve a balance between a long cycle life and low-temperature performance,the effects of different electrolytes on rate performance,high-and low-temperature discharge performance,charge retention capacity,cycle life,low-temperature cycle performance,and EIS were compared and analyzed by adjusting the components of the electrolyte solvent.The results demonstrated that the design of the electrolyte composition had a significant impact on the performance of the battery.By partially replacing the carbonate esters and the short-chain carboxylic esters with long,linear carboxylic esters having a low melting point,impressive low-temperature performance as well as high-temperature stability were achieved,which illustrated that EP and PP play an important role in the cyclic stability of the LCO/C electrode system.The solvent component EC+EP+PP(mass ratio 2∶5∶3)exhibited the best comprehensive performance.The developed LTB battery maintained a discharge capacity retention of 99.86% at 5C and a discharge capacity retention of 92.84% at-40℃ and 1C.After 1000 cycles,the low-temperature discharge capacity at-40℃ and 1C was still 90% of the initial low-temperature discharge capacity.At room temperature,the cycling retention rate reached 85%after 1500 cycles;at a low temperature of-10℃,the cycling retention rate was 82.4% after 500 cycles.

关 键 词：低温 18650电池 电解液 循环寿命 锂离子电池 

分 类 号：TM912.9[电气工程—电力电子与电力传动]