Excellent performance in lithium-ion battery anodes: rational synthesis of Co(CO3)0.5(OH)0.11H2O nanobelt array and its conversion into mesoporous and single-crystal Co3O4.

Abstract

Herein, we report a rational method to synthesize a Co3O4 nanobelt array on a conducting substrate and functionalize it in the application of Li-ion battery anodes, which is a novel and facile approach to access the nanobelt array of transition metal oxides. Compared to the previous reports, the as-prepared samples in our experiments exhibited both mesoporosity and single-crystallinity, and meanwhile, good contact with the conducting substrate (via a thin layer of TiO2) provided an express pathway for charge transfer when they were applied in Li-ion batteries without any need to add other ancillary materials (carbon black or binder) to enhance the system's conductivity and stability. Under the condition of high charge-discharge current density of 177 mA/g in Li-ion batteries' testing, the Co3O4 nanobelt array was capable of retaining the specific capacity of 770 mAh/g over 25 cycles. Moreover, even though the charge-discharge rates were increased to 1670 and 3350 mA/g, it still could have reached the stable retention of the specific capacity of 510 and 330 mAh/g beyond 30 cycles, respectively, indicating an obtainable excellent rate capability. More importantly, the improved performance in Li-ion battery testing was definitely ascribed to the unique structures in our samples after elaborate analysis. So the final conclusion would be given that the lab-synthesized Co3O4 nanobelt array potentially could be a highly qualified candidate for Li-ion battery anodes in some practical fields, where high capacity and good capability are strictly required.