A precious-metal free micro fuel cell accumulator

► Alkaline fuel cell type micro accumulator as on-chip energy storage using non-precious metals for hydrogen storage (LaNi5) and oxygen electrode (La0.6Ca0.4CoO3). ► Simplified cleanroom fabrication process. ► Combination with micro energy harvesting devices. ► High power output (0.66mWcm−2) and high capacity (>1mAhcm−2). In recent years, integrated fuel cell (FC) type primary and secondary batteries attracted a great deal of attention as integrated on-chip power sources due to their high theoretical power densities. Unfortunately, the costs of these devices have been rather high. This is partially due to the involved clean-room processes, but also due to the fact that these devices generally rely on expensive precious-metals such as Pd and Pt. Therefore we developed a novel integrated FC type accumulator that is based on non-precious-metals only. The key component of the presented accumulator is its alkaline polymer electrolyte membrane that allows not only the usage of a low-cost AB5 type hydrogen storage electrode, but also the usage of La0.6Ca0.4CoO3 as a precious-metal free bifunctional catalyst for the air-breathing electrode. Additionally the presented design requires only comparatively few cleanroom processes which further reduces the overall production costs. Although abdicating precious-metals, the presented accumulator shows an open circuit voltage of 0.81V and a maximum power density of 0.66mWcm−2 which is comparable or even superior to former precious-metal based cells.