C-S hybrids prepared by electrodeposition and thermal diffusion methods from kapok-based amorphous carbon flakes as the cathode materials of Li-S batteries

Kapok-based carbon nanoflakes (KCNs) were prepared by high-temperature calcination of kapok fibers as the carbon source. Electrodeposition or thermal diffusion were used to load sulfur onto the KCNs to obtain S-C hybrids for use as the cathode materials of Li-S batteries. The effect of the preparation method on the microstructure and electrochemical properties of the hybrid was investigated. It was found that small sulfur particles are evenly distributed on the surface of KCNs by electrodeposition while a sulfur layer is formed by thermal diffusion. The electrodeposited and thermally loaded C-S hybrids respectively deliver initial discharge capacities of 1 199.7 and 714.7 mAh·g^-1 at a current density of 100 mA·g^-1, which drop to 623.0 and 367.7 mAh·g^-1 after 200 cycles. The sulfur particles formed by electrodeposition have a higher utilization rate and stronger chemical bonding to the carbon than the sulfur formed by thermal diffusion, and this decreases the loss of sulfur during cycling.