Novel synthesis method of cobalt hydroxycarbonate hydrate-reduced graphene oxide composite microspheres for lithium-ion battery anode

Transition metal compounds (TMCs) consisting of multiple anions are considered as efficient anode materials for lithium-ion batteries (LIBs) owing to their characteristic of transforming into multiple metal compounds with single anions during the first cycle. Nanostructured composites of TMCs with multiple anions and a conductive carbon component can enhance lithium-ion storage through the synergistic effects of the formation of heterointerfaced structures, structural stability, and high conductivity. Herein, cobalt hydroxycarbonate hydrate-reduced graphene oxide (CoHC-rGO) composite microspheres are introduced. The spray pyrolysis process facilitates formation of cobalt chloride-rGO composite precursor powders. The prepared precursor powders are finally converted into CoHC-rGO composites through in-situ precipitation within the microspheres. The conversion mechanism of CoHC-rGO with lithium ions is systemically scrutinized via rational in-situ and ex-situ analyses. Uniquely structured CoHC-rGO microspheres exhibit better electrochemical properties than the bare CoHC nanopowders. The CoHC-rGO microspheres have high reversibility of 440 mA h g⁻¹ at 1500th cycle even at 5 A g⁻¹.