Thus, in going from a current density of 0.1 A cm -2 to 0.5 A cm -2 to 1 A cm -2 , the overpotential at the anode changed from 240 mV to 294 mV to 329 mV; a total increase of 89 mV. By contrast, the overpotential at the cathode changed, in the same sequence, from 93 mV to 248 mV to 383 mV; a total increase of 290 mV. Accordingly, the performance of the cell was dominated by the anode at low current densities, but increasingly by the cathode at high current densities.