Correlation of Structural Disorder with the Reversible Discharge Capacity of Nickel Hydroxide Electrode

Hydrothermal treatment of a slurry of badly crystalline (betabc) nickel hydroxide at different temperatures (65-170DGC) results in the progressive ordering of the structure by the step-wise elimination of disorders. Interstratification is eliminated at 140DGC, while cation vacancies are eliminated at 170DGC. A small percentage of stacking faults continue to persist even in 'crystalline' samples. Electrochemical investigations show that the crystalline nickel hydroxide has a very low (0.4 e/Ni) reversible charge storage capacity. An incidence of at least 15% stacking faults combined with cation vacancies is essential for nickel hydroxide to perform close to its theoretical (1 e/Ni) discharge capacity.