Development and Characterization of a Dithionite / Air Fuel Cell
Here we would like to report a work in which we have built and studied an alkaline fuel cell with the inexpensive redox couple dithionite / sulfite.
Anode: S2O42- + 4 OH- -> 2 SO32- + 2 H2O + 2 e- E0= -0.294 V
Cathode: O2 + 2 H2O + 4 e- -> 4 OH- E0= +1.227 V
Cell: 2 S2O42- + O2 + 4 OH- -> 4 SO32- + 2 H2O E = 1.530 V
As with the VOFC the reactions in a separate or the same cell may be reversed, and thus serve as an energy storage. For investigating the feasibility of such a cell a carbon-based anode and a platinum catalyst cathode for the ORR was used. The investigations were carried out by means of polarization curves, discharge tests and impedance spectroscopy using the cell voltage and the half-cell potentials and showed a maximum power density of 2 mW/cm² at room temperature. Under these conditions the oxidation of dithionite at carbon was much slower than the ORR. With a 0.85 M Na2S2O4the cell reached 12.4% energy efficiency and an energy density of 8.6 Wh/L.
1 C. Menictas, M. Skyllas-Kazacos, Journal of Applied Electrochemistry 2011, 41, 1223–1232.
2 S. S. Hosseiny, M. Saakes, M. Wessling, Electrochemistry Communications 2011, 13, 751–754.
3 J. grosse Austing, C. Nunes Kirchner, E.-M. Hammer, L. Komsiyska, G. Wittstock, Journal of Power Sources 2015, 273, 1163–1170.