Synthesis mechanism of lithium nickel oxide using hydrothermal-electrochemical method: Thermodynamic modelling and experimental verification

Potential-pOH diagrams of nickel are drawn at various temperatures to predict the reaction of nickel in a 4 M lithium hydroxide solution. Based on these diagrams, the thermodynamic stability of each constituent of nickel in 4 M LiOH solution at various temperatures is evaluated. The oxidation mechanism is studied based on the thermodynamic analysis and the oxidation proceeds in the following order: Ni, Ni(OH)2 or HNiO2−, NiOOHH2O, NiOOH, LiNiO2. The thermodynamic model is validated experimentally by the cyclic voltammogram method.