Mesoporous carbon spheres with tunable porosity prepared by a template-free method for advanced lithium-sulfur batteries

摘要

Mesoporous carbon spheres (MCS) with tunable porosity are prepared by a mass-producible spray-drying process using chitosan as carbon precursor with ethanol as porosity tuning agent. By this template-free method, MCSs with different porosity are deduced by manipulating the volume ratio of ethanol in the solvent for chitosan. The resulted MCSs show controllable surface areas, pore volumes and bimodal pore size distribution. They are employed as substrates for the preparation of sulfur/carbon composite cathode. Electrochemical performance of the MCSs with 50 wt% sulfur loading is investigated. One of the S/MCS composite cathodes displays initial discharge capacity of 1163 mAhg~(-1), excellent rate capability of 510 mAhg~(-1) at 2 C and good cycling stability of 715 mAhg~(-1) after 100 cycles at 0.2 C. The sulfur loading content could reach as high as 60%, while it still could deliver a capacity of 642mAhg~(-1) after 100 cycles at 0.2 C.