Lifetime and residual capacity estimate for Lithium-ion secondary cells for stationary use in telecommunications systems

Abstract:
We estimated the lifetimes of large–capacity lithium-ion secondary cells in high-temperature-acceleration tests under variable maintaining voltages. The decrease in capacity was exacerbated by the temperature increase, and we found a strong correlation between the lifetime and temperature, in agreement with Arrhenius' law. The lifetime, which was effected by the charge voltage, was over 10 years at 25deg C, obtained by maintaining the cells at an appropriate charge voltage. The internal cell resistances were observed to increase in the tests and the increases were governed by the maintaining temperature. Charge voltages had little effect on the resistances. The residual capacity and internal resistance under a fixed charge voltage are correlated, and the internal resistance measurements might be useful for estimating residual capacities.