One-pot method for synthesizing spherical-like metal sulfide-reduced graphene oxide composite powders with superior electrochemical properties for lithium-ion batteries

A facile, one-pot method for synthesizing spherical-like metal sulfide-reduced graphene oxide (RGO) composite powders by spray pyrolysis is reported. The direct sulfidation of ZnO nanocrystals decorated on spherical-like RGO powders resulted in ZnS-RGO composite powders. ZnS nanocrystals with a size below 20 nm were uniformly dispersed on spherical-like RGO balls. The discharge capacities of the ZnS-RGO, ZnO-RGO, bare ZnS, and bare ZnO powders at a current density of 1000 mAg^-1 after 300 cycles were 628, 476, 230, and 168 mAhg^-1, respectively, and the corresponding capacity retentions measured after the first cycles were 93, 70, 40, and 21%, respectively. The discharge capacity of the ZnS-RGO composite powders at a high current density of 4000 mAg^-1 after 700 cycles was 437 mAhg^-1. The structural stability of the highly conductive ZnS-RGO composite powders with ultrafine crystals during cycling resulted in excellent electrochemical properties.