One-Pot Synthesis of CoSex-rGO Composite Powders by Spray Pyrolysis and Their Application as Anode Material for Sodium-Ion Batteries

A simple one-pot synthesis of metal selenide/reduced graphene oxide (rGO) composite powders for application as anode materials in sodium-ion batteries was developed. The detailed mechanism of formation of the CoSex-rGO composite powders that were selected as the first target material in the spray pyrolysis process was studied. The crumple-structured CoSex-rGO composite powders prepared by spray pyrolysis at 800 degrees C had a crystal structure consisting mainly of Co0.85Se with a minor phase of CoSe2. The bare CoSex powders prepared for comparison had a spherical shape and hollow structure. The discharge capacities of the CoSex-rGO composite and bare CoSex powders in the 50th cycle at a constant current density of 0.3Ag(-1) were 420 and 215mAhg(-1), respectively, and their capacity retentions measured from the second cycle were 80 and 46%, respectively. The high structural stability of the CoSex-rGO composite powders for repeated sodium-ion charge and discharge processes resulted in superior sodium-ion storage properties compared to those of the bare CoSex powders.