Lab-size rechargeable metal hydride–air cells

Lab-size rechargeable metal hydride–air (MH–air) cells with a gas management device were designed in order to minimize the loss of electrolyte. An AB5-type hydrogen storage alloy was used as anode materials of the MH–air. The thickness of the metal hydride electrodes was in the range of 3.0–3.4 mm. Porous carbon-based air electrodes with Ag2O catalysts were used as bi-functional electrodes for oxygen reduction and generation. The electrodes were first examined in half-cells to evaluate their performance and then assembled into one MH–air cell. The results showed the good cycling stability of the rechargeable MH–air cell with a capacity of 1990 mAh. The discharge voltage was 0.69 V at 0.05–0.1 C. The charge efficiency was about 90%. The specific and volumetric energy densities were about 95Wh kg−1 and 140 Wh L−1, respectively.