Nanofabrication of selenium/reduced graphene oxide composite with sulfur doping via solution co-impregnation for enhanced lithium-selenium batteries

Lithium-selenium batteries are still plagued by polyselenides dissolution and low utilization of active material. In the present work, sulfur-doped selenium/reduced graphene oxide composite (Se68-S9/rGO) was successfully designed and prepared by solution co-impregnation of selenium and sulfur within the rGO matrix, and further used as cathode materials in lithium-selenium batteries. The introduction of sulfur could form the CAS chemical bond and the stable chemical bond between selenium and sulfur, which effectively limit the leaching of higher order soluble polyselenides intermediate as well as immobilizing Se, further enhancing the rate performance and the cycling stability of the Se68-S9/rGO cathode. With high selenium and sulfur content of ca. 80%, the Se68-S9/rGO cathode can achieve a capacity of 538 mA h g-1 after 200 cycles at a current density of 0.5 C, and a capacity of 473 mA h g-1 after 200 cycles at a current density of 1 C, exhibiting superior cycling performance.