Preparation, Comparative Energy Storage Properties, and Impedance Spectroscopy Studies of Environmentally Friendly Cathode, Li(MMn11/6)O4 (M = Mn1/6, Co1/6, (Co1/12Cr1/12))

Undoped and doped lithium manganese oxides, Li(MMn11/6)O-4 (M = Mn-1/6, Co-1/6, and (Co1/12Cr1/12)), were prepared by the simple polymer precursor route at different temperatures. The compounds were characterized by X-ray diffraction, SEM, density, BET surface area, and electroanalytical techniques. The energy storage performance of the compounds differs with the preparation temperature and doped elements, such as Co and Cr. The compound, Li(Co1/6Mn11/6)O-4, was found to give a better energy storage performance than LiMn2O4 and Li((Co1/12Cr1/12)Mn-11/6)O-4. For a high current density of 600 mA g(-1), Li(Co1/6Mn11/6)O-4 prepared at 650-850 degrees C delivered a discharge capacity of 65-100 (+/- 3) mAh g(-1) at the end of 200-1000 cycles. Excellent capacity retention was noted in all cases. The comparative impedance spectroscopy studies were made and the mechanisms were discussed.