An Eco-friendly Microorganism Method to Activate Biomass for Cathode Materials for High-Performance Lithium-Sulfur Batteries

Biomass-based carbon has attracted considerable attention as a host material of active sulfur in lithium-sulfur batteries, while chemical activators of H₃PO₄, KOH, or ZnCl₂ are essential to construct the porous structure of the materials. Inspired by traditional Chinese steamed buns, herein a unique porous microcellular carbon composed of cross-linked nanopores has been synthesized by an eco-friendly biological fermentation using banana peel as a carbon precursor. The specially hierarchical carbon framework obtained under the aerobic respiration and anaerobic breathing of biological yeast during fermenting, and simultaneously the inherent doping of N (3.28 at. %), produce a promising carbon host material to stabilize the structure of electrodes and restrict the dissolution of polysulfides during charging and discharging. The amount of biological yeast has an important influence on the microstructure of the biomass carbons and the correlated electrochemical properties of carbon/sulfur electrodes. The optimal amount of biological yeast is 3.0 wt %, where the carbon/sulfur composite electrode possesses a sulfur loading of 74.34 wt % and achieves a large initial reversible capacity of 1174 mAh g^-1 at 0.1 C and a high capacity hold of 58.35% after 100 cycles. Our study provides a novel eco-friendly strategy to fabricate the interconnected hierarchical porous carbon framework from living wastes for various energy storage and conversion applications, including lithium-ion battery, supercapacitor, etc.