An understanding of anomalous capacity of nano-sized CoO anode for advanced Li-ion battery

Nanostructured transition metal oxides are of great interest as a new generation of anode materials for high energy density lithium-ion batteries. In this work, research has been focused on the nano-sized (grain size similar to 7 nm) CoO anode material and this material delivers charge capacity of 900 mAh g(-1) that exceeds the theoretical value of 715 mAh g(-1). Possible reason for this unaccounted and unexplained anomalous capacity of the nano-sized CoO material has been suggested by thermogravimetric analysis. A mechanism for this interesting behavior has been systematically evaluated by using X-ray absorption spectroscopy. The anomalous capacity is proposed to be associated with the formation of oxygen-rich CoO material. The results obtained from the nano-sized CoO material have been compared with relatively larger-sized material (grain size similar to 32 nm). (C) 2010 Published by Elsevier B.V.