After repeated shallow discharging and overcharging of nickel or cadmium capacity‐limited cells, a working voltage lowering of the discharge curve was observed. The magnitude of the lowering was higher in the nickel capacity‐limited cells. The x‐ray diffraction pattern of the charged‐state normal nickel electrode contained diffraction peaks due only to β‐NiOOH. A charged‐state nickel electrode showing a lowered discharge voltage had diffraction peaks due to γ‐NiOOH, in addition to those due to β‐NiOOH.This may be a cause of the memory effect observed in practical nickel‐cadmium batteries.

Possible Cause of the Memory Effect Observed in Nickel-Cadmium Secondary Batteries. -The magnitude of working voltage lowering of the discharge curve observed after repeated shallow discharging and overcharging of nickel or cadmium capacity-limited cells is higher in the former cells. These cells show X-ray diffraction peaks characteristic for γ-NiOOH in addition to those for β-NiOOH, the sole component of charged-state normal Ni electrodes. The voltage lowering which appears to correspond to the first stage of the classic memory effect in practical batteries, thus seems to be attributable to γ-NiOOH formation in the Ni electrode. -(SATO, Y.; ITO, K.; ARAKAWA, T.; KOBAYAKAWA, K.; J.