Three-dimensionally scaffolded Co3O4 nanosheet anodes with high rate performance

Advances in secondary batteries are required for realization of many technologies. In particular, there remains a need for stable higher energy batteries. Here we suggest a new anode concept consisting of an ultrathin Co3O4 nanosheet-coated Ni inverse opal which provides high charge–discharge rate performance using a material system with potential for high energy densities. Via a hydrothermal process, about 4 nm thick Co3O4 nanosheets were grown throughout a three-dimensional Ni scaffold. This architecture provides efficient pathways for both lithium and electron transfer, enabling high charge–discharge rate performance. The scaffold also accommodates volume changes during cycling, which serves to reduce capacity fade. Because the scaffold has a low electrical resistance, and is three-dimensionally porous, it enables most of the electrochemically active nanomaterials to take part in lithiation–delithiation reactions, resulting in a near-theoretical capacity. On a Co3O4 basis, the Ni@Co3O4 electrode possesses a capacity of about 726 mAh g−1 at a current density of 500 mA g−1 after 50 cycles, which is about twice the theoretical capacity of graphite. The capacity is 487 mAh g−1, even at a current density of 1786 mA g−1. [Display omitted] •Three-dimensionally scaffold-based anodes are fabricated.•Thin nanosheets provide efficient pathways for electron and ion transportation.•The Co3O4 anodes show attractive C-rate performance.•The robust electrode structure provides high capacity retention.