CuCo₂O₄ Hollow Microspheres with Graphene Composite Targeting Superior Lithium-Ion Storage

CuCo₂O₄, a type of promising lithium-ion storage material, exhibits high electrochemical properties in lithium-ion batteries and enormous economic benefits. However, its practical application is limited by problems such as structural collapse and electrochemical stability during the charging and discharging process. In this work, the reduced graphene oxide (rGO)-coated CuCo₂O₄ (CuCo₂O₄/rGO) hollow microspheres were successfully prepared by electrostatic self-assembly. The CuCo₂O₄/rGO electrode shows an outstanding capability for lithium-ion storage and a remarkable rate capacity, e.g., 445 mA h g^-1 at 5 A g^-1. After 150 cycles at 0.1 A g^-1, the reversible capacity of the CuCo₂O₄/rGO electrode is as high as 1080 mA h g^-1, and it can still retain about 530 mA h g^-1 in the 400th cycle at 1 A g^-1. The hollow microspheres with mesoporous shells can cause electrolyte penetration into the spherical shell to effectively shorten the transfer distance of lithium ions, and the encapsulation of graphene improves the conductivity and stability of CuCo₂O₄, which endows CuCo₂O₄/rGO with a wonderful Li⁺ storage performance. It is proved that this is an efficient method to improve the electrochemical performance of metal compounds for better applications in energy storage.