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

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.