A High Power Density, High Efficiency Hydrogen-Chlorine Regenerative Fuel Cell with a Low Precious Metal Content Catalyst

We report the performance of a hydrogen-chlorine electrochemical cell with a chlorine electrode employing a low precious metal content alloy oxide electrocatalyst for the chlorine electrode: (Ru_0.09Co_0.91)_3O_4. The cell employs a commercial hydrogen fuel cell electrode and transports protons through a Nafion membrane in both galvanic and electrolytic mode. The peak galvanic power density exceeds 1 W cm^-2, which is twice previous literature values. The precious metal loading of the chlorine electrode is below 0.15 mg Ru cm^-2. Virtually no activation losses are observed, allowing the cell to run at nearly 0.4 W cm^-2 at 90% voltage efficiency. We report the effects of fluid pressure, electrolyte acid concentration, and hydrogen-side humidification on overall cell performance and efficiency. A comparison of our results to the model of Rugolo et al. [Rugolo et al., J. Electrochem. Soc., 2012, 159, B133] points out directions for further performance enhancement. The performance reported here gives these devices promise for applications in carbon sequestration and grid-scale electrical energy storage.