Suppression of the memory effect observed in alkaline secondary batteries under partial charge–discharge conditions

Under partial charge–discharge cycling conditions at a state of charge (SoC) of 50–70%, a greater effect on the suppression of the memory effect, which occurs in rechargeable alkaline batteries containing a Ni-electrode, was observed using conductive materials such as nano-sized Co(OH)2 and CoO powders in the Ni-electrode. The nano-sized Co(OH)2 powder, prepared by the reverse micelle method, consisted of approximately 15–60 nm spherical-shaped particles. The Ni–Cd cells containing approximately 15- or 20-nm-sized Co(OH)2 powder and 18 nm CoO powder in the Ni-electrode did not show any memory effect after a 150-cycle partial charge–discharge cycling test, and γ-NiOOH, which is mainly the origin of the memory effect, was not detected in the Ni-electrode, whereas the Ni–Cd cell containing the same content of 500 nm Co(OH)2 powder and 18 nm CoO in the Ni-electrode showed the memory effect. The nano-sized Co(OH)2 powder could be more homogeneously dispersed in the Ni-electrode when compared to the 500 nm powders and might develop a superior electro-conductive network between the Ni(OH)2 particles.