Here we report evaluation of the performance of various types of carbon electrodes and redox behavior with vanadium electrolyte solution by potential-sweep coulometry method. This technique expanded the voltage-step coulometry method which we reported previously [4]. Other electrolytes such as organic redox solution and Ti-Mn were also evaluated by this method [2].
Figure 1 showed the model of the half-cell of the small-scale test cell for potential-sweep coulometry. Electrolyte solution was filled up in the test cell and then stopped, and the current and amount of electricity were measured during for the potential sweep to positive and negative potentials. Figure 2 showed current-potential responses of carbon felt electrode measured in vanadium solution (0.1 M VOSO4/ 3.5 M H2SO4) with different potential sweep rate (0.1, 0.2, and 0.5mV/s). In this case, electrochemical reaction of this carbon felt electrode showed good responses for both charging and discharging process. We also investigated other electrolytes and other carbon felt and paper electrodes.