Improved cycling stability of lithium–sulfur batteries using a polypropylene-supported nitrogen-doped mesoporous carbon hybrid separator as polysulfide adsorbent

• A functional hybrid separator with a N-doped mesoporous carbon layer was prepared.
• N-dopants on carbon-coating chemically immobilize sulfur-related species.
• The functionalized hybrid separator enhanced the overall performance of Li–S cells.
• Excellent cycle stability with ultralow decay rate of 0.037% per cycle was obtained.
• Li–S cells with a hybrid separator delivered a high areal capacity of 3 mAh cm−2.

The lithium/sulfur couple is garnering tremendous interest as the next-generation of cost-efficient rechargeable battery systems capable to fulfill emerging energy storage demands. However, the viable commercialization of lithium–sulfur (Li–S) batteries is still an obstacle by fast capacity fading and poor cycling stability mostly caused by the polysulfide shuttle and active sulfur material loss. In this contribution, we show that the surface modification of the commercial polypropylene separator with a nitrogen-doped mesoporous carbon enhances the interfacial interaction between the N-dopants on carbon-coating and the sulfur-related species by coupling interactions. These unique physical and interfacial chemical properties of the N-doped mesoporous carbon-coating promote the chemical adsorption and confinement of lithium (poly)sulfide intermediates in the cathode side, improving the active material utilization and hence the overall electrochemical performance of Li–S batteries: high initial discharge capacity of 1364 mAh g−1 at 0.2C and notable cycling stability with high reversible capacity of 566 mAh g−1 and negligible degradation rate of 0.037% after 1200 cycles at 0.5C. Furthermore, despite the use of a simple-mixed sulfur-carbon black cathode with high-sulfur loading of 3.95 mg cm−2, the cell with a hybrid separator delivers a high areal capacity of ∼3 mAh cm−2.

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