Optimization for the Formation of Metal Hydride Electrode Used in Ni/MH Batteries

Abstract

The effect of charging current, temperature, concentrations of KOH and LiOH, soaking time and temperature on the utilization of metal hydride (MH) electrode in the formation of Ni/MH battery is investigated by the conventional experimental design. The experimental results indicate that the optimal charging conditions are the charging time ratio of 9/1 with 0.1 and 1.0 C-rates. The other optimal conditions for the formation of MH electrode re 25°C, 8.02 M KOH and 0.48 M LiOH aqueous solution. The steady utilization of MH electrode is 83.52% for the soaking temperature of 45°C and the soaking time greater than 24 h, respectively. According to the Taguchi's orthogonal arrays, the relationship between the utilization of metal hydride electrode (y) and the formation factors is obtained to be y = 75.52 - 6.58A + 3.98C + 5.09E + 6.71F - 1.32AC + 2.57BC + 5.62E2 - 10.67F2 where A, B, C, E and F are the charging current, the charging temperature, the concentration of KOH in the electrolyte, the soaking time and temperature, respectively. Under the optimal formation conditions, the utilization of MH electrode is increased from 87.25% to the steady value of 98.50% by increasing the charging/discharging cycle from 1 to 4.