Synthesis by molten salt and cathodic properties of Li(Ni_1/3Co_1/3Mn_1/3)O₂

Abstract

The mixed oxide, Li(Ni_1/3Co_1/3Mn_1/3)O₂, with the layer structure has been prepared by a one-pot method using the molten-salt mixture, LiNO₃-LiCl at temperatures 750, 850 and 950 °C in air. The compounds were characterized by a variety of techniques. As per Rietveld data, only 4.0 and 2.5% of 'cation-mixing' was observed in the compounds prepared at 850 and 950 °C, respectively. Cyclic voltammetry with Li metal as counter electrode showed a clear indication of Ni^2+/4+ redox couple at ~3.6-3.9 V in all compounds. Charge-discharge cycling was carried out in the range 2.5-4.3, 2.5-4.4 and 2.5-4.5 V versus Li at a current rate of 20 or 30 mA g⁻¹. The fifth cycle discharge capacities varied from 125 to 145 (±5) mA h g⁻¹ for the compounds prepared at 850 and 950 °C. They exhibited excellent capacity-retention without noticeable capacity-fade till 50 cycles irrespective of the voltage cut-off.