Hierarchically mesoporous flower-like cobalt oxide/carbon nanofiber composites with shell–core structure as anodes for lithium ion batteries

Hierarchically mesoporous flower-like Co3O4/carbon nanofiber (Co3O4/CNF) composites with a shell–core structure for use as an anode material for lithium ion batteries were prepared through electrophoretic deposition on electrospun CNF, followed by annealing in air. The flower-like Co3O4 shell on the surface of the CNF core formed a highly porous three-dimensional (3D) structure with a large surface area of 332 m2 g−1 and a mesoporous surface area of 176 m2 g−1. The Co3O4 shells provided abundant inner spaces through the development of mesopores, which facilitated the diffusion of lithium ions and also suppressed the volume expansion to some extent, leading to high specific capacities. The rate capability was also increased as a result of CNF having a one-dimensional pathway, which enhanced the electrical conductivity and structural stability. After the initial capacity of 1446 mAh g−1, the specific capacity leveled off at 911 mAh g−1 without showing capacity fading even after 50 cycles. Exceptional percent recovery was observed with the flower-like mesoporous 3D morphology. The electrochemical stability was maintained through the cushioning effect created by the CNF via elastic deformation when the Co3O4 shell expanded its volume and compressed the CNF radially.