Experiments Setup
Sealed lead acid cells 2 V, 5 Ah (Cyclon Enersys®) were tested in this
study at -10, 0, 25 and 40 °C (Figure 1a). Studies on these temperature
margins are sufficient to provide better understanding of SLA cell
performance. The thermal chamber (ESPEC, BTU-433) was used for testing
cells in a controlled environment (Figure 1b). A programmable battery
tester (Arbin Instruments, BT-1) was used for charge/discharge cycling
studies. The charge and discharge cut-off potential were kept at 2.45
and 1.85 V, with a constant charging and discharging rate of C/10 (0.5
A) and a 5 min rest period between charging and discharging cycles. The
discharge rate was taken to study the slow charge discharge phenomena.
Discharge capacities were calculated for each cycle from the charge and
discharge profiles. EIS spectra were recorded after 20/25
charge-discharge cycles in fully charged state at room temperature using
a potentiostat/galvanostat (PARSTAT 2273, Princeton Applied Research)
with a frequency range of 10 Hz to 1 kHz.