新型锂盐Li[N(SO_2OCH(CF_3)_2)_2]电解液的表征与性能

Characterization and properties of the electrolyte using Li[N(SO_2OCH(CF_3)_2)_2] as conductive salt

以双(1,1,1,3,3,3-六氟异丙氧基磺酰)亚胺钾(K[N(SO2OCH(CF3)2)2],KHFPSI)和LiClO4为原料,在极性非质子溶剂中进行复分解反应制备高纯度的双(1,1,1,3,3,3-六氟异丙氧基磺酰)亚胺锂(Li[N(SO2OCH(CF3)2)2],LiHFPSI),利用核磁共振(NMR)、红外光谱(FTIR)、元素分析(EA)和离子色谱(IC)对其进行结构表征及杂质分析,并通过交流阻抗、循环伏安、线性电位扫描以及计时电流法等方法对LiHFPSI-EC/EMC(3:7,v/v)电解液体系的物化和电化学性质进行了系统的研究.结果表明,LiHFPSI电解液具有较高的耐氧化电位(5.7V vs.Li+/Li),良好的Al箔钝化性能,并与人造石墨有较好的相容性;采用LiHFPSI电解液的石墨/LiCoO2锂离子电池体现出较传统导电盐LiPF6更好的循环性能以及容量保持能力.

High purity of lithium bis[（1,1,1,3,3,3-hexafluoro-2-propoxy） sulfonyl]imide （LiHFPSI） was prepared by the metathesis reaction of KHFPSI with LiC104 in dimethyl carbonate （DMC） solvent, and confirmed by NMR, IR and EA methods. Impurity content of the object compound was also analyzed by ion chromatography. Moreover, the physicochemical and electrochemical properties of the LiHFPSI-EC/EMC （3：7, v/v） electrolytes, including the viscosity, conductivity, thermal stability, and electrochemical stability to A1 and Pt electrodes, were investigated by means of EIS, CV, LSV, chronoamperometry and so on. It was concluded that the LiHFPSI based electrolyte was rather resistant toward anodic oxidation and able to passivate the AI anode during the polarity process. Li/C half cells investigation indicated that LiHFPSI was compatible well with graphite cathode. And the C/LiCoO2 Li-ion cells using LiHFPSI as conductive salt showed better cycling properties and the less capacity loss than that using LiPF6 as conductive salt.