A Convenient Synthesis Route for CoO Hollow Microspheres and Their Application as a High Performing Anode in Li-Ion Batteries.

A new, rapid, and cost-effective method for synthesizing hollow microspheres (HMSs) of cobalt oxide (CoO) using the phloroglucinol-formaldehyde gel route is reported here. Further, the synthesized hollow CoO microspheres were investigated as an anode material for Li-ion batteries. The CoO hollow spheres exhibited excellent electrochemical performance and cycling stability, for example, a capacity of 915 mA h g was obtained at 1 C rate over 350 cycles. The material also exhibited good performance at high rates, viz., capacities of 500, 350, and 250 mA h g at 10 C, 25 C, and 50 C, respectively, with good capacity retention over 500 cycles. The excellent electrochemical performance of CoO can be ascribed to the porous nanoarchitecture that provides a short diffusion length for Li ions and high electrolyte percolation in the porous structure. Additionally, the thin porous wall of the nanocages provides an effective way to overcome the issues associated with the volume change occurring during Li charge/discharge. The conversion of CoO into Co upon discharge was also probed by measuring the magnetic properties.