A novel permselective organo-polysulfides/PVDF gel polymer electrolyte enables stable lithium anode for lithium–sulfur batteries

Lithium–sulfur (Li–S) battery can satisfy the need of the future power battery market because of its high energy density, but the hidden dangers caused by lithium anode have seriously hindered their commercialization. Herein, an innovative gel polymer electrolyte (GPE) composed of polyvinylidene fluoride (PVDF) and organo-polysulfide polymer (PSPEG) is proposed, which could be used in semi-solid-state Li–S batteries for protection of Li anodes. Particularly, organo-polysulfide polymer could chemically/electrochemically generate both inorganic and organic components simultaneously in-situ once contacting fresh Li metal surface and/or during discharging processes. And these inorganic/organic components could participate in the formation of the SEI layer and finally constitute a stable and flexible hybrid SEI layer on the surface of Li metal anode. Moreover, the organic components were permselective to lithium ions against anions. Therefore, PVDF/PSPEG GPE ensures the ideal chemical and electrochemical properties for Li–S batteries. Our work demonstrates an effective solution to solve the problems about Li anodes and contributes to the development of the safe Li metal batteries. A PVDF-based GPE modified by organo-polysulfide polymer (PSPEG) with a large number of -S x - bonds promotes lithium ion transport and enables stable lithium anode for lithium–sulfur batteries.