Lithium Bis(fluorosulfonyl)imide/Poly(ethylene oxide) Polymer Electrolyte for All Solid-State Li–S Cell

Solid polymer electrolytes (SPEs) comprising lithium bis(fluorosulfonyl)imide (LiN(SO 2 F) 2 , LiFSI) and poly(ethylene oxide) (PEO) have been studied as electrolyte material and binder for the Li–S polymer cell. The LiFSI-based Li–S all solid polymer cell can deliver high specific discharge capacity of 800 mAh g sulfur –1 (i.e., 320 mAh g cathode –1 ), high areal capacity of 0.5 mAh cm –2, and relatively good rate capability. The cycling performances of Li–S polymer cell with LiFSI are significantly improved compared with those with conventional LiTFSI (LiN(SO 2 CF 3 ) 2 ) salt in the polymer membrane due to the improved stability of the Li anode/electrolyte interphases formed in the LiFSI-based SPEs. These results suggest that the LiFSI-based SPEs are attractive electrolyte materials for solid-state Li–S batteries.