An adsorption-catalytic conversion catalyst Fe2O3@C-modified separator for boosting conversion of lithium polysulfides and long-life lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are a highly promising energy storage system due to their ultra-high theoretical energy density. However, Li-S batteries, based on the dissolved deposition mechanism, suffer from lithium polysulfides (LiPSs) shuttling and slow conversion kinetics, causing severe capacity decay during operation. Herein, we have improved the battery life by a LiPSs adsorption-rapid catalytic conversion Fe2O3@C catalyst in the modified separator. The Fe2O3@C modified separator first physically restricts LiPSs and then rapidly converts the captured LiPSs through the polar adsorption and catalytic ability of Fe2O3, greatly promoting the LiPS conversion kinetics in Li-S batteries. The battery with Fe2O3@C exhibits excellent electrochemical performance. In detail, the initial discharge specific capacity of the first discharge is 1043.26 mAh g(-1) at 0.05 C; the specific capacity is maintained at 676.80 mAh g(-1) after 100 cycles at 0.2 C. The high specific capacity of 389.3 mAh g(-1) is maintained even after 1000 cycles with a capacity decay of 0.055% per cycle. This work provides a way to improve sulfur conversion kinetics through metal oxides.