Tailored graphene-encapsulated mesoporous Co3O4 composite microspheres for high-performance lithium ion batteries

Abstract

Graphene-encapsulated mesoporous Co₃O₄ microspheres have been successfully fabricated through a facile self-assembly approach. Driven by the mutual electrostatic interactions, the mesoporous Co₃O₄ microspheres prepared by a nanocasting method are fully wrapped by graphene shells. We performed the evaluation as anode materials for Li-ion batteries: the composites exhibit a first discharge capacity of 1533 mA h g⁻¹ and rapidly stabilize while remaining at a reversible capacity up to 820 mA h g⁻¹ during all the discharge–charge cycles at a current of 100 mA g⁻¹. The substantially improved electrochemical performance of the Co₃O₄–graphene composites were ascribed to the synergistic effects between the conductive graphene shells and mesoporous Co₃O₄ microspheres. Notably, the graphene shells not only act as buffers to accommodate the volume variation of Co₃O₄ but also serve as the reliable conductive channels of the electrode. In addition, the mesostructure of the mesoporous Co₃O₄ microspheres provides extra space for the storage of Li⁺ and significantly reduces paths for both Li⁺ ion and electron diffusion.