Nanorod In2O3@C Modified Separator with Improved Adsorption and Catalytic Conversion of Soluble Polysulfides for High-Performance Lithium–Sulfur Batteries

The shuttle effect of soluble lithium polysulfides (LiPSs) poses a crucial challenge for commercializing lithium–sulfur batteries. The functionalization of the separator is an effective strategy for enhancing the cell lifespan through the capture and reuse of LiPSs. Herein, a novel In2O3 nanorod with an ultrathin carbon layer (In2O3@C) was coated on a polypropylene separator. The results demonstrate the adsorption and catalysis of In2O3 on polysulfides, effectively inhibiting the shuttle effect and improving the redox kinetics of LiPSs. Besides, the ultrathin carbon layer increases the reaction sites and accelerates the electrochemical reaction rate. The cell with the In2O3@C interlayer displays excellent reversibility and stability with a 0.029% capacity decay each cycle in 2000 cycles at 2C. In addition, the In2O3@C interlayer significantly improves the cell performance under high current (888.2 mA h g–1 at 2C and room temperature) and low temperature (1007.8 mA h g–1 at 0.1C and −20 °C) conditions.