Endoplasmic-reticulum-like catalyst coating on separator to enhance polysulfides conversion for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with high theoretical specific energy of 2600 Wh kg⁻¹ are one of promising candidates for next-generation energy storage devices. However, the severe shuttle effect of intermediate polysulfides leads to rapid capacity decay during battery cycling, especially at high sulfur loading and high current density. Herein, the MnO nanoparticles covered carbon with endoplasmic-reticulum-like structure (MnO@ERC) as separator coating for Li-S batteries is proposed. The MnO@ERC coating can act as upper current collector to enhance electrical conductivity of cathode and decrease the interface impedance of the whole battery. More importantly, both the polar MnO nanoparticles and Mn₃O₄ formed at the end of the charging process can catalyze the conversion of lithium polysulfides, which is convinced by the high adsorption energy and the elongate S–S bond. As a result, Li-S batteries based on MnO@ERC coating separator showed stable cycle for 350 cycles under 0.5C, high discharge specific capacity of 783.6 mAh g⁻¹ after 100 cycles at 0.2 C, 534.7 mAh g⁻¹ after 100 cycles under the sulfur loading of 5.26 mg cm⁻² and low self-discharge rate of 9.1% after resting 48 h.