A Bio-Inspired Structurally-Responsive and Polysulfides-Mobilizable Carbon/Sulfur Composite as Long-Cycling Life Li-S Battery Cathode

High energy density Li-S battery has attracted wide attention because of its promising application in long driving-range electric vehicles. However, the shuttle effect of polysulfides, electrical insulation and volume-change of sulfur, remain great challenges. Herein, inspired from a natural mimosa pudica structure, we present a novel nanocomposite which consists of a mimosa pudica-structured carbon matrix coating with sulfur. The biomimetic configuration is able to structurally-respond to the volume-change of sulfur during charge/discharge; and the carbon matrix provides a good conductivity for rapid electron transfer. The carbon/sulfur composite-based Li-S batteries exhibit a good electrochemical performance including a stable capacity after 1000 cycles, along with a Coulombic efficiency as high as 99.6 %, and an excellent rate-performance even after three rounds of measurements. In addition, the density function theory modeling is investigated, which confirms the adsorption effect of carbon towards the polysulfides including Li2S4, Li2S6, and Li2S8, enabling a long-term cycling stability.