Formation of LiNixCo1−xO2 by decarbonization of organic gel precursors through treatment with nitric acid and hydrogen peroxide

We have used a complex sol–gel process to synthesize a family of compounds LiNixCo1−xO2 (x = 0, 0.25, 0.5, 0.75, 1). These compounds are candidates for electrode materials in high-energy-density batteries. Starting sols were prepared from xNi2+ + (1 − x) Co2+ acetates/ascorbic acid aqueous solutions by alkalizing with LiOH and NH3. With thermal treatment in air, nickel carbonates formed in quantities roughly proportional to Ni concentration. The carbonate impurities could not be fully removed by heating in air to high temperatures. Because formation of pure layered oxides was inhibited by the presence of the carbonates, we developed a new way to remove them from just-formed precursors by treating the intermediate phases (those formed after calcination at 750 °C) with concentrated HNO3 and H2O2. All resulting powders were phase pure by X-ray diffraction and were easily friable. Various electrochemical properties of compacts prepared from these powders were measured.