Study on the effects of temperature, deposition cycle number, and cobalt additives on the properties of the positive active material in nickel-cadmium batteries

This study investigates the effects of deposition temperature, number of deposition cycles, and cobalt (Co) additives on the structural and electrochemical properties of the positive active material in nickel–cadmium (Ni–Cd) batteries. The purpose is to optimize fabrication parameters to enhance material utilization efficiency and battery performance. Electrodes were fabricated by impregnating porous nickel substrates with nickel nitrate solution, followed by chemical conversion in potassium hydroxide under varying temperatures (65 – 80 °C) and repeated for different cycle numbers (1 – 5). A cobalt nitrate post-treatment was applied to selected samples. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and hydrostatic weighing methods were employed to characterize microstructure, composition, density, and porosity. Charge–discharge performance was evaluated using prototype Ni–Cd cells. Results show that the optimal deposition temperature range is 70 – 75 °C, which promotes uniform active material distribution and high density while maintaining sufficient porosity. Four deposition cycles yielded the best balance between mass loading and structural stability. The addition of cobalt improved utilization efficiency by approximately 5.2% and reduced internal resistance from 7.15 mΩ to 4.85 mΩ. These findings provide a scientific basis for improving Ni–Cd electrode fabrication, and future studies may explore long-term cycling behavior and alternative conductive additives.