Self-assembly of Co3V2O8 multilayered nanosheets: controllable synthesis, excellent Li-storage properties, and investigation of electrochemical mechanism.

Developing electrode materials with both high energy and power densities holds the key for satisfying the urgent demand of energy storage worldwide. Herein, we demonstrate the successful preparation of Co3V2O8 nanostructures that are constructed from self-assembly of ultrathin nanosheets via a simple hydrothermal method followed by annealing in air at 350 °C for 2 h. A "slipping-exfoliating-self reassembly" model based on the time-dependent experiments was proposed to elucidate the formation of the hierarchical nanosheets. When tested as lithium ion anodes, the as-synthesized multilayered nanoarchitectures exhibit outstanding reversible capacity (1114 mA h g(-1) retained after 100 cycles) and excellent rate performance (361 mA h g(-1) at a high current density of 10 A g(-1)) for lithium storage. Detailed investigations of the morphological and structural changes of Co3V2O8 upon cycling reveal an interesting kinetics toward lithium ion intercalations, where reversible conversion reactions between Co and CoO are found proceeding on the amorphous lithiated vanadium oxides matrixes. We believe that this observation is a valuable discovery for metal vandates-based lithium ion anodes. The superior electrochemical performances of the multilayered Co3V2O8 nanosheets can be attributed to the unique morphologies and particularly the surface-to-surface constructions that are generated during the lithium ion insertion processes.