(655b) Carbon Coated Co3O4 as High Power Anode for Lithium Battery Applications

Today's world of modernization and miniaturization lays greater emphasis on more power from smaller and lighter battery packs. Among the competing systems, rechargeable lithium batteries show the highest energy density, due to the high reducing power of lithium that leads to large cell voltage. The limitations in the overall performance of Li-ion batteries depend on the intrinsic performances of the materials (anode, cathode and electrolyte) and the technology aspects (material processing, electrode fabrication and battery conception), taking into consideration of the environment of each material in the complete cell. Tremendous amount of work has been done worldwide in these two directions over the last twenty years. The active anode material of a secondary Li-ion battery is a host material into / from which lithium can be reversibly inserted / extracted over a composition range. Currently, carbonaceous materials are widely used as anodes in Li-ion batteries because of their low cost, even discharge characteristics and low operating voltage. Generally, the commercialized carbonaceous anodes though have found widespread applications, problems like the high irreversible capacity, swelling behavior or failure of the electrode through intercalation of propylene carbonate (PC) based electrolyte and the formation of surface electrolyte interface (SEI) layer, remain as severe unsolved problems till date. Disruption of this SEI layer in conventional Li-ion batteries is a primary source of capacity and power fade. Recent advances in the synthesis of tin (Sn), silicon (Si), nickel (Ni), cobalt (Co), and their corresponding oxides as replacements for carbon-based anodes have resulted in batteries with higher specific capacity and enhanced cycle life. Based on this ground, we have made an attempt to exploit carbon coated Co3O4 as anode for high power lithium battery applications. Herein, hydrothermal method has been used to synthesize monodisperesed spherical Co3O4 particles and subsequent carbon coating using glucose as the carbon source. Experimental: Monodispersed, spherical Co3O4 particles was synthesized by the ammonia assisted hydrothermal method at 180 °C and the carbon coating to the synthesized Co3O4 particles was done using glucose as the carbon source at the same temperature. Electrochemical properties of the synthesized C- Co3O4 material was evaluated using a 2032 type coin cell. The cell was assembled in an argon-filled glove box and charged and discharged between 0.5 and 3.0 V at room temperature. Results and discussion Figure 1 shows the surface morphology and the cyclic voltammetry studies of the C-Co3O4 material. It is interesting to note that the ammonia assisted hydrothermal synthesis methodology has produced spherical Co3O4 particles with well defined grain boundary. Carbon coating of ~10nm is obvious from the TEM images obtained. When deployed as anode in lithium-ion batteries, the C-Co3O4 has delivered an excellent cycle life as well as rate capability behavior. The various physical and electrochemical parameters of the synthesized compounds are discussed in detail.