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.