A functional additive to in-situ construct stable cathode and anode interfaces for all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries (ALSBs) using poly(ethylene oxide) (PEO)-based composite solid-state electrolytes (CSEs) are regarded as one of potential high energy storage devices; however, they still face two core problems of polysulfide shuttle and lithium dendrite during long cycle. Herein, based on a passive-type strategy, magnesium bis(trifluoromethylsulphonyl)imide [Mg(TFSI)(2)] as a novel functional additive of the PEO-Li6.5La3Zr1.5Ta0.5O12 (PEO-LLZTO)-based CSE, has been proved to be successful on both retarding poly -sulfide species shuttle and stabilizing lithium anode. Study results show that magnesium polysulfide precipitate, formed on the interface between the S/C cathode and CSE, can hinder the shuttle of diffluent lithium polysulfide; and meanwhile, a robust LixMg layer generated on the surface of lithium anode can suppress the formation of dendrite. As a consequence, the Mg(TFSI)(2) additive-functionalized PEO-LLZTO CSE obviously prompts a critical current density up to 1.0 mA cm(-2) from 0.6 mA cm(-2) of the sole PEO-LLZTO CSE, and maintains very stable cycling over 500 h at 0.2 mA cm(-2) for a symmetric cell. Furthermore, the ALSB with the Mg(TFSI)(2) additive-functionalized PEO-LLZTO CSE delivers robust cycle performances, with specific capacities of 877 mAh g(-1) at 0.1C (1C = 1675 mA g (1)) after 50 cycles (capacity retention ratio of 100 %) and 331 mAh g (1) at 0.5C over 300 cycles (capacity retention ratio of 94.1 %) under 50 degrees C. This work provides a realistic reference in designing novel additives to ameliorate the electrode-electrolyte interfaces for stabilizing ALSB.