Synthesis and electrochemical properties of Cr and V-substituted Li₂Mno₃ as cathode materials for secondary lithium batteries

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[Mn_1-2xCr_xV_x]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. Li_1.596[Mn_0.806Cr_0.181V_0.013]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.