Enhancement of the performance of a proton battery

The present paper reports on experiments to improve theoretical understanding of the basic processes underlying the operation of a ‘proton battery’ with activated carbon as a hydrogen storage electrode. Design changes to enhance energy storage capacity and power output have been identified and investigated experimentally. Key changes made were heating of the overall cell to 70 °C, and replacement of the oxygen-side gas diffusion layer with a much thinner titanium-fibre sheet. A very substantial increase in reversible hydrogen storage capacity to 2.23 wt%H (598 mAh g−1, 882 J g−1) was achieved. This capacity is nearly three times that of the earlier design, and more than double the highest electrochemical hydrogen storage using an acidic electrolyte previously reported. It is hypothesised that the main cause of the major gain in storage is an enhanced water formation reaction on the O-side through reduced flooding. In addition, an alternative mode of discharging a proton battery has been discovered that allows direct generation of hydrogen gas from the hydrogenated carbon material, by a ‘hydrogen-pump’ type of reaction. The hydrogen gas evolved is high purity, and thus may ultimately create opportunities for use of this storage technology in hydrogen supply chains for fuel cell vehicles.