Conclusion:
The sealed lead acid (SLA) cells were cycled at -10, 0, 25 and 40 °C to
evaluate the performance and degradation mechanism. Discharge profiles
demonstrated that the ageing is faster at elevated temperature (40 °C)
than at lower temperature (-10, 0, & 25 °C). However, capacity
degradation is minimal at 0 and -10 °C due to reduced active material
availability. Moreover, EIS analysis revealed that impedance change was
significantly higher at 25 and 40 °C as compared to that at 0 and -10
°C. The charge transfer resistance is relatively more governing factor
than ohmic resistance for indicating the degradation of the cell. XRD
analysis revealed that a permanent deposition of SO4 due
to surface hardening (usually termed as sulfate hardening) in the cells
after cycling at all the temperatures. However, sulfate hardening is
significantly higher at 25 and 40 °C as compared to that at 0 and -10 °C
as confirmed from Pb/S ratio determined from EDS analysis. The study
demonstrates that temperature of operation plays a crucial role in state
of health prediction of sealed lead -acid batteries.