High density Co3O4 nanoparticles confined in a porous graphene nanomesh network driven by an electrochemical process: ultra-high capacity and rate performance for lithium ion batteries

Here, we report a novel Co3O4-graphene hybrid electrode material with high density Co3O4 nanoparticles (NPs) in a size range of 2-3 nm confined in a few-layered porous graphene nanomesh (PGN) framework driven by an electrochemical process. Raman spectra indicate that Co species preferentially anchor on the defective sites of the PGN, which results in markedly reduced irreversible Li storage and therefore significantly enhanced coulombic efficiency. The ultra-small Co3O4 NPs provide a large surface area and a short solid-state diffusion length, which is propitious to achieving a high Li ion capacity at high rate. Also, the few-layered graphene network with high electronic conductivity not only permits easy access to the high surface area of the Co3O4 NPs for the electrolyte ions, but also serves as a reservoir for high capacity Li storage. As a result, the Co3O4-PGN composite layers deliver an ultra-high capacity (1543 mA h g(-1) at 150 mA g(-1)) and excellent rate capability (1075 mA h g(-1) at 1000 mA g(-1)) with good cycling stability.