Three-dimensional laminated carbon-sulfur composite cathodes derived from Trichoderma spores for lithium-sulfur batteries

The commercialization of lithium-sulfur (Li-S) batteries is limited by the poor electrochemical properties under actual working conditions, which is mainly due to the slow cathodic redox kinetics and serious polysulfides shuttling. In this work, we report a novel free-standing sulfur cathode to address aforementioned issues, in which sulfur is encapsulated in Trichoderma spores derived carbon hosts (TC) with the assistance of supercritical CO2 (SC-CO2) fluid technology. This free-standing sulfur cathode has a "sandwich" structure with three-dimensional (3D) highly conductive network constructed by reduced graphene oxide (rGO). SC-CO2 fluid with superior solubility, high permeability and rapid diffusion can achieve the uniform distribution of sulfur and high sulfur loading in TC/S composites. Meanwhile, the novel "sandwich" structure not only provides high mechanical strength, but also inhibits soluble polysulfide shuttling, as well as improves redox kinetics of sulfur. As a result, a reversible discharge capacity of > 755 mA h g(-1) after 100 cycles at 0.1 A g(-1), and a high Coulombic efficiency of 97.9% can be achieved at high areal S loading (3 mg cm(-2)). This work offers a new perspective on the electrode structure design of high loading sulfur cathode for high energy density Li-S batteries.