Journal of Power Sources, Vol.244, 561-564, 2013
Electrochemical properties of transition metal substituted calcium ferrite-type Li-x(M0.1Mn0.9)(2)O-4 (M = Ni, Ti)
Transition metal substituted CaFe2O4-type Lix(M0.1Mn0.9)(2)O-4 (M = Ni, Ti) was synthesized by Na/Li ion exchange method from high-pressure synthesized CaFe2O4-type Na(M0.1Mn0.9)(2)O-4 (M = Ni, Ti). The crystal structures were refined by Rietveld analysis using powder X-ray diffraction data. The electrochemical properties were measured. The initial discharge capacities of Li-x(Ni0.1Mn0.9)(2)O-4 and Li-x(Ni0.1Mn0.9)(2)O-4 were 1193 and 122.0 mAh g(-1) in the range of 4.8-3.0 V (vs Li/Li+). The capacities of substitutions were 5.29% and 7.68% increased than the value of Li0.81Mn2O4. After 50 charge-discharge cycles, the discharge capacities of Li0.81Mn2O4 and Li-x(Ni0.1Mn0.9)(2)O-4 were 5.78% and 11.1% decreased from the initial. The Ni substitution was effective for increasing the discharge voltage, although the effect was decreased with increasing cycle numbers. (C) 2013 Elsevier B.V. All rights reserved.
Keywords:Lithium manganese oxide;Positive electrode;High-pressure;Ion exchange;CaFe2O4-type;Crystal structure