Hierarchical Co3O4 Nanoparticles Embedded in a Carbon Matrix for Lithium-Ion Battery Anode Materials

• Co3O4 nanocrystals with size of 20 nm homogeneously embedded in the carbon matrix are successfully synthesized.
• Cycle exceeds 400 times in half cells at a 5 C (5 Ag−1) rate while retaining about 1000 mAhg−1 reversible capacities.
• Large rates up to 10 C for are achieved with high energy density.
• Such Co3O4 exhibits excellent high-rate capability and cycling stability.

A Co3O4-C nanocomposite has been synthesized by a one-step hydrothermal method free of any template with an annealing process. The composite exhibits a flower-like, hollow, and porous skeleton with a large specific surface area of 272.3 m2g−1. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images reveal the hybrid nanostructure comprises ring-like Co3O4 nanocrystals of 20 nm in diameter homogeneously embedded in the carbon matrix. Such integrated electrodes exhibit an ultrahigh specific capacity and excellent cycling stability even at a high charge/discharge current density. Cycle exceeds 400 times in half cells at a 5 C (5 Ag−1) rate while retaining about 1000 mAhg−1 reversible capacities (where a 1 C rate represents a one-hour complete charge or discharge). This study not only provides a simple synthesis method for lithium ion batteries, but also helps in designing novel and high performance electrode materials.