Electrochemical properties of transition metal substituted calcium ferrite-type Lix(M0.1Mn0.9)2O4 (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.