全氟电解液与硅碳负极的副反应及改性策略  

Side reaction and modification strategy of perfluoro electrolytes with Si/C anode

作　　者：张雪 苑志祥 杨志林 周倩 张波涛[1] ZHANG Xue;YUAN Zhixiang;YANG Zhilin;ZHOU Qian;ZHANG Botao(School of Chemical Engineering,Qingdao University,Qingdao,Shandong 266071,China;Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciences,Qingdao,Shandong 266101,China)

机构地区：[1]青岛大学化学化工学院,山东青岛266071 [2]中国科学院青岛生物能源与过程研究所,山东青岛266101

出　　处：《电池》2024年第4期450-454,共5页Battery Bimonthly

摘　　要：氟代碳酸乙烯酯(FEC)是锂离子电池常用的添加剂,可改善长循环稳定性,但在电解液中添加的质量分数大于10%时,会导致电池严重产气,带来安全隐患并影响电池寿命。以1 mol/L二氟草酸硼酸锂(LiDFOB)/FEC为基础电解液,研究在SiO_(x)/石墨(Si/C)负极表面的产气和界面副反应,并引入聚氨酯(PU)来缓解Si/C负极与电解液之间的界面副反应。FEC会在负极表面发生持续分解,并生成CO_(2)和H_(2)。在电解液中加入PU后,Si/C负极的体积膨胀得到抑制,可抑制固体电解质相界面(SEI)膜的破裂与重建,减少FEC与负极的接触,从而缓解界面副反应,改善电解液的电化学性能。Li|Si/C电池以0.5 C倍率在0.001~1.500 V可稳定循环200次,容量保持率为74.98%。Fluoroethylene carbonate(FEC)is a popular additive for Li-ion battery,which can improve long-cycle stability.However,when the addition of FEC in the electrolyte exceeds 10%of mass fraction,it can lead to severe gas production,which causes safety hazards to the battery and affects the lifetime of battery.The gas generation and interfacial side reactions of SiO_(x)/graphite(Si/C)anode are researched using 1 mol/L lithium difluoro-oxalate borate(LiDFOB)/FEC as the base electrolyte,and polyurethane(PU)is introduced to alleviate side reactions between Si/C anode and the electrolyte.The decomposition of FEC on the anode surface continues to generate CO_(2)and H_(2).The volume expansion of Si/C anode is suppressed with the addition of PU,which can inhibit the rupture and reconstruction of solid electrolyte interface(SEI)film,avoid the contact between FEC and anode,thus alleviate the interface side reactions and the electrochemical performance of the electrolyte is improved.The Li|Si/C battery can be stably cycled for 200 times at a rate of 0.5 C in 0.001-1.500 V,the capacity retention rate is 74.98%.

关 键 词：锂离子电池 电解液 全氟电解液 硅碳负极 氟代碳酸乙烯酯(FEC) 聚氨酯(PU) 界面副反应 

分 类 号：TM912.9[电气工程—电力电子与电力传动]