Effect of storage on performance of SUPER nickel-cadmium cells

A study was undertaken to examine the capacity maintenance features of SUPER nickel-cadmium cells when stored for extended periods to determine whether the features change when the same kind of positive plates as that used in nickel-hydrogen cells are used. The cells maintained their capacity when stored at 0/spl deg/C in the discharged state and at 0/spl deg/C in the charged state by continuously trickle charging. There was a capacity loss when stored in the open-circuit condition at 28/spl deg/C. A cycling test at 17 percent depth of discharge for 2400 cycles using cells stored at various conditions showed that cells maintained good end of discharge voltage regardless of their storage history. However, the EOD voltages of stored cells were lower by 10 mV compared to those of fresh cells. The capacity at the end of the cycling test decreased for the stored cells by 2-7 Ah. The storage related capacity loss is lower for SUPER Ni-Cd cells compared to that of Ni-H/sub 2/ cells containing a hydrogen precharge. The results suggest the pivotal role of hydrogen pressure in the capacity loss phenomenon.