Low-Cost Biomass-Gel-Induced Conductive Polymer Networks for High-Efficiency Polysulfide Immobilization and Catalytic Conversion in Li–S Batteries

Lithium–sulfur batteries are regarded as one of the most promising candidates for next-generation energy storage systems because of their high energy density and the low cost of sulfur. However, practical applications are still impeded by sluggish redox kinetics and the shuttling effect of soluble intermediate lithium polysulfides (LiPSs), which induces irreversible loss of active materials, self-discharge, and thus poor cycle stability. Herein, a polysulfide-anchored catalytic polymer is reported to solve the shuttling behavior and improve battery performance. Natural polymer xanthan gum and konjac gum with abundant polar oxygen-containing functional groups (−OH, C═O, −COOH, and −O−) that induce strong binding interactions with lithium polysulfide and reduce the energy barrier of the reaction from S8 to Li2S are entangled with a conductive carbon nanotube (CNT) skeleton as a polysulfide shielding interlayer. Combined with the highly conductive CNT porous network that facilitates Li+ ion transportation, the CNT–biomass gel interlayer is endowed with great capability of adsorbing and catalyzing the active sulfur. Benefiting from these synergistic attributes, the as-obtained CNT–biomass gel composite interlayer can achieve excellent performance of a high initial capacity of 998.2 mA h g–1 at 0.2C and a slight capacity decay of 0.078% per cycle at 0.5C over 200 cycles. More importantly, the battery demonstrates a cycle stability at a high sulfur loading of 3.0 mg cm–2. The proposed strategy will contribute to the design of biomass-derived materials for Li–S batteries. Natural polymer xanthan gum and konjac gum with abundant polar oxygen-containing functional groups that induce strong binding interactions with lithium polysulfide and reduce the energy barrier of the reaction from S8 to Li2S are entangled with a conductive carbon nanotube skeleton as a polysulfide shielding interlayer. The CNT–biomass gel interlayer is endowed with a great capability of adsorbing and catalyzing the active sulfur.