Engineering conductive and catalytic triple-phase interfaces for high efficiency polysulfides conversion in Li-S batteries

The well-known shuttle effect of lithium polysulfides (LiPSs) in the ether-based liquid electrolyte and polymer solid electrolytes are the main roadblocks of Li-S batteries to perform high discharge capacity with a long cycling lifespan. Herein, a triple phase interface among carbon/catalysts (vanadium single atoms (VSAs) and metallic cobalt nanoparticles (CoNPs))/electrolyte is proposed for the high-performance Li-S batteries. At the triple-phase interfaces, the LiPSs are chemically immobilized and electrocatalytically transformed into insoluble Li2S at the rate-determining process of liquid–solid conversion. The nucleation and growth of Li2S precipitates were dominated by the interface chemistry and the dispersion of catalysts (3D reconstruction image). In the Li-S batteries with liquid ether-based electrolytes, a discharge capacity of 1343 mAh g−1 was achieved at 0.1 C and the decay of capacity was decelerated with 0.05% per cycle for 500 cycles at 1 C, as well as superb rate capability (808 mAh·g−1 at 5 C). The triple phase interfaces also exhibited high performance in solid state Li-S batteries with solid polymer electrolytes, which the discharge capacity reaches 1289 mAh·g−1 at 0.05 C and 849 mAh·g−1 at 0.5 C.