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 mA g(-1) after 300 cycles were 628, 476, 230, and 168 mA h g(-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 mA g(-1) after 700 cycles was 437 mA h g(-1). The structural stability of the highly conductive ZnS-RGO composite powders with ultrafine crystals during cycling resulted in excellent electrochemical properties.