Dithionite/air direct ion liquid fuel cell

The feasibility of an alkaline S2O42−/air-fuel cell was evaluated at room temperature, using a cell with an anion exchange membrane and a platinum oxygen reduction reaction catalyst. The tests performed were open circuit voltage analysis, linear sweep voltammetry, discharge analysis and electrochemical impedance spectroscopy (EIS) with registration of anode half-cell potential. With 0.85 M Na2S2O4 in 2 M KOH, the cell achieved a maximum power density of 2 mW cm−2, and the open circuit cell voltage was about 0.9 V. In a potentiostatic discharging at 0.2 V cell voltage, an energy efficiency of 12.3% was achieved at an energy density of 8.6 Wh L−1. The low power density was mainly due to the low reaction kinetics of dithionite oxidation at graphite electrodes. The low energy efficiency was mainly caused by a low cathode potential, which probably resulted from mixed potential formation and the low anode kinetics.