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 Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 basis, the Ni@Co 3 O 4 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 . [ABSTRACT FROM AUTHOR]