Preparation and electrochemical characteristics of a new Li-Mn-V-O system formed from heat-treatment of a MnO2, NH4VO3 and LiNO3 mixture

Abstract

New quarternary oxides (Li2O) x · MnO2 · yV2O5 (x = 0.125 ∼ 0.25, y = 0.125 ∼ 0.25), formed by heating mixtures of MnO2, NH4VO3 and LiNO3 at various Li/Mn and V/Mn atomic ratios and at different temperatures (300 ∼ 400 °C in air, have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy (ESCA) and infrared spectroscopy. The quarternary oxide with x = 0.25 and y = 0.25 showed a discharge capacity of 220 A h (kg oxide)−1 and an energy density of ca. 600 W h (kg oxide)−1 at a current density of 0.20 mA cm−1 in 1 m LiClO4-propylene carbonate at 25 °C. When charge-discharge cycling with the (Li2O) · MnO2 · 0.25V2O5 electrode was performed at a constant capacity of 30 A h (kg oxide)−1 and at a constant current density of 0.10 0.20 mA cm−2, the electrode sustained over 100 cycles at a high mean discharge potential of ca. 3 V vs Li/Li+.