硫系电解液添加剂对镍钴锰酸锂//石墨锂离子电池性能的影响

Effects of sulfur-containing electrolyte additives on the performance of lithium nickel cobalt manganese oxide//graphite Li-ion batteries

本工作系统研究了6种添加剂[碳酸亚乙烯酯(VC)、亚硫酸乙烯酯(ES)、硫酸乙烯酯(DTD)、1,3-丙二醇环硫酸酯(PCS)、1,3-丙烷磺酸内酯(PS)、1,3-丙烯磺酸内酯(PST)]对镍钴锰酸锂(NCM111)//石墨体系锂离子电池电化学性能的影响,通过对比首次充放电效率、放电容量、倍率特性、低温放电能力、高温存储性能以及循环寿命等发现:VC在各方面性能比较均衡,碳碳双键(C=C)能够改善成膜特性,循环性能优异,可独立使用;ES在化成、循环和存储过程中因电解液持续分解而胀气,无法单独使用;硫酸酯添加剂(DTD和PCS)能够明显降低阻抗并提升低温性能,但高温性能稍差;磺酸内酯添加剂(PS和PST)对抑制高温胀气效果突出,含有双功能基团的PST循环性能及抑制电压衰减的能力优于PS,但低温阻抗较高。综合对比发现,单组分硫系添加剂在某些性能方面有自己的特色,但也存在显而易见的缺陷,无法独立使用。通过与VC进行等比例复配,硫系添加剂循环性能差的问题得以解决,而高首效、低内阻、大倍率和高温稳定性等特色功能得以保持,二元联用后的综合性能显著优于单组分添加剂,采用添加剂联用方式来改善电池综合性能是较佳选择。

The effects of six electrolyte additives:vinylene carbonate(VC),ethylene sulfite(ES),ethylene sulfate(DTD),1,3-propanediol cyclo-sulfate(PCS),1,3-propylene sultone(PS),1,3-propylene sultone(PST)on the electrochemical performance of lithium nickel cobalt manganese oxide(NCM111)//graphite lithium-ion batteries were investigated herein.Some conclusions were obtained by comparing the results of the first charging-discharging efficiency,discharged capacity,rate characteristics,low-temperature discharging capability,high-temperature storage performance and cycle life,etc.C=C double bond can improve the film-forming property and promote the cycle life,making VC possess a relatively balanced performance in all aspects and can be used independently.The continuous gas production for ES in the formation,cycle,and storage processes can be observed because of the unstoppable decomposition of the electrolyte,making it impossible to use.Sulphate Additives(DTD and PCS)can significantly reduce the DCR and improve the low-temperature performance;however,their high-temperature performance is slightly restricted.Sulfonate additives(PS and PST)have outstanding effects in inhibiting high-temperature flatulence.Especially,PST with dual functional groups has better cycle performance and capability to suppress the voltage decay in high-temperature environments than PS but has higher impedance in low-temperature environments than other additives.A comprehensive comparison shows that the single component sulfur-containing additive is equipped with unique characteristics in some properties but also has obvious defects,making it lonely and impossible.The problem of poor cycling performance of sulfur-containing additives can be solved by proportionally compounding them with VC,while their characteristics such as high initial coulombic efficiency,low internal resistance,excellent rate performance and high-temperature stability can be maintained.The comprehensive performance of binary combination is better than that of the single-component additive,making it a better choice for additive combination to improve the battery performance.