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.