Lithium bis(fluorosulfonyl)imide/poly(ethylene oxide) polymer electrolyte

• Published in: Electrochimica acta 2014-07, Vol.133, p.529-538
• Main Authors: Zhang, Heng, Liu, Chengyong, Zheng, Liping, Xu, Fei, Feng, Wenfang, Li, Hong, Huang, Xuejie, Armand, Michel, Nie, Jin, Zhou, Zhibin
• Format: Article
• Language: English
• Subjects: Battery; Electrodes; Electrolytes; Electrolytic cells; Ionic conductivity; Lithium; Lithium bis(fluorosulfonyl)imide; Lithium polymer battery; Molecular weight; Oxides; Poly(ethylene oxide); Solid polymer electrolytes
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2014.04.099

New solid polymer electrolytes (SPEs) comprising of lithium bis(fluorosulfonyl)imide (LiFSI) and high molecular weight poly(ethylene oxide) (PEO, Mv=5×106gmol−1) have been prepared and characterized, and are comparatively studied with the representative SPEs, Li[N(SO2CF3)2] (LiTFSI)/PEO, at a molar ratio of EO/Li+=20. Their physicochemical properties have been investigated in terms of phase transition behavior, ionic conductivity, lithium-ion transference number (tLi+), electrochemical stability, and with particular attention to the interfacial behavior between lithium electrode and SPEs. It has been demonstrated that the ionic conductivities of LiFSI/PEO electrolyte are higher than those of LiTFSI/PEO one above 60°C, and exceeds 10−3 S cm−1 at 80°C. The interface resistances of Li symmetric cell (Li metal | polymer electrolytes | Li metal) using LiFSI/PEO electrolyte are much lower than those using LiTFSI/PEO. The Li/LiFePO4 cell using LiFSI/PEO electrolyte exhibits good cycling performance at 80°C. These outstanding properties of the LiFSI/PEO electrolyte make it attractive as SPEs for Li battery.