Synthesis and electrochemical performance of Li₂V_xMn_1−xO₃ positive electrode for lithium batteries

Lithium excess manganese oxide, namely, Li₂MnO₃ is under investigations to improve its electrochemical performance as the next generation high capacity electrode material. Partial substitution of Mn by another metal is one of the ways to influence the properties of Li₂MnO₃. In the present study, vanadium is used to partially substitute Mn in various ratios. Li₂V_xMn_1−xO₃ (x = 0.1, 0.2, 0.3 and 0.4) samples are prepared by sol–gel method using stoichiometric ratios weights of Mn(CH₃COO)₂·4H₂O, Li₂CO₃ and NH₄VO₃. The crystalline phases are identified by X-ray diffraction. The particles morphology is studied with a scanning electron microscope. Furthermore, impedance measurements (EIS) are applied using frequency range between 10⁶ and 10⁻² Hz. The optimum EIS is obtained with for the Li₂V_0.3Mn_0.7O₃ cell. Cyclic voltammetric measurements are carried out for the lithium manganate materials between 0.01 and 4.5 V versus Li⁺ with scan rate 0.1 mV s⁻¹. Also, galvanostatic charging and discharging cycling of the cells are achieved with the same potentials windows using charging and discharging current intensity of 10 mA g⁻¹ between 1.5 and 4.5 V versus Li⁺. It is observed that Li/Li₂V_0.3Mn_0.7O₃ cell has higher specific discharge capacity, 227 mAh g⁻¹ rather than the other cells.