Functionalized hierarchical porous carbon with sulfur/nitrogen/ oxygen tri-doped as high quality sulfur hosts for lithium-sulfur batteries

A novel tri-doped hierarchical porous carbon (PC) for sulfur host is prepared by pyrolysis of a commercial gelatin and a facile template process. And, sulfur-porous carbon (S@PC) composite as cathode material of lithium sulfur battery is synthesized by a melt diffusion method. The as-prepared PC has both strongly physical adsorption and tightly chemical bonding of polysulfides due to high porosity with the interlacement of micropores, mesopores and macropores/macrohollows, large surface area, and rich heteroatom tri-doping, resulting in an excellent electrochemical performance as a sulfur host for lithium sulfur battery cathodes. Among the synthesized S@PC composites, due to the optimum melting time, S@PC 12 h composite electrode has more effective nitrogen-containing and oxygen-containing groups, and stronger S-O bonds than other S@PC composites. As a result, S@PC 12 h composite electrode shows a high initial specific discharge capacity of 1471 mAhg(-1) at 0.1C rate, a super rate capacity of 790 mAhg(-1) at 1C after 20 cycles of low rate, an excellent long cycle stability at 1C. Appropriate macropores and/or macrohollows can not only provide charge transfer channels, but also effectively adsorb crystalline sulfur to a certain extent, result in the improvement of electrochemical performance for S@PC composites. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

A novel tri-doped hierarchical porous carbon for sulfur host was prepared by pyrolysis of gelatin and a facile template process, and a sulfur-porous carbon composite was synthesized as cathode material for lithium sulfur battery via melt diffusion. The composite electrode with optimum melting time showed high specific discharge capacity, super rate capacity, and excellent long cycle stability, attributed to the effective nitrogen-containing and oxygen-containing groups and strong S-O bonds. The appropriate macropores and/or macrohollows not only provided charge transfer channels, but also effectively adsorbed crystalline sulfur, leading to improved electrochemical performance.