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.