In an attempt to improve the electrochemical performance of Li2MnO3 cathode, Cr and V are substituted for Mn via an aqueous reduction reaction followed by heating in air. Li3VO4 and Li2CrO4 impurities in the as-prepared Li2[Mn1-2xCrxVx]O3 (0 ≤ x ≤ 0.2) samples are removed by washing with deionized (DI) water. Although the washed samples have deficient metal contents, monoclinic layered structures are obtained. Li1.596[Mn0.806Cr0.181V0.013]O3 has a composite phase of Li2MnO3 • LiCrO2 • LiVO2 • Li4Mn5O12 and can deliver more than 225mAh/g of discharge capacity above 2.5 V vs. Li at 10mA/ g. Structural changes due to the oxygen loss are minimized, and excellent cycle performance and rate capability have been achieved.
Keywords: Secondary lithium batteries, Cathode materials, Li2MnO3, Doping, Structure, Electrochemical properties