Preparation of gelatin-derived nitrogen-doped large pore volume porous carbons as sulfur hosts for lithium-sulfur batteries

Gelatin-derived N-doped porous carbons (GPCs) with a large pore volume were synthesized by a method combining templating, freeze-drying and carbonization, using amino acid rich gelatin as the carbon and nitrogen sources, and silica sol and ice as the templates. The pore volume of the GPCs was regulated by adjusting the mass ratio of the silica sol to ice. Lithium polysulfide (LiPS) adsorption experiments show that the materials have a strong chemisorption for LiPSs. Electrochemical measurements show that N-doping accelerates the sulfur reduction kinetics and inhibits the shuttling of LiPSs. In addition, the larger the pore volume of the GPC, the better the cycling stability of the sulfur cathode. A highly N-doped (7.00%) GPC with a pore volume of 2.98 cm³ g⁻¹ could adsorb a high sulfur content of 78.4% and had a high sulfur utilization rate. Its composite with sulfur as a cathode material gave a high initial specific capacity of 1 384 mAh g⁻¹ at 0.1 C, which dropped to 608 mAh g⁻¹ after 100 cycles.