Recyclable Metal Air Fuel Cells Using Sintered Magnesium Paste with Reduced Mg Nanoparticles by High-Repetitive Ns Pulse Laser Ablation in Liquid

Abstract

An energy cycle using solar power and metals has been proposed. High repetitive laser pulses are generated by a solar-pumped laser or a laser generated using solar power, and the laser pulses are irradiated to metal oxides in liquid. We can obtain reduced metal nanoparticles with this method, and solar power is effectively stored as chemical energy. We succeeded in producing sintered Mg metal paste. The sintered Mg nanopaste reduced Mg nanoparticles from pure MgO or Mg(OH)2 powder, collected from used Mg air cells, by laser ablation in liquid using a high-repetitive ns pulse Nd:YAG laser. We also fabricated metal air fuel cells using sintered Mg plates as negative electrodes. Electricity was successfully produced from these cells. A light-emitting diode and a motor were connected to the Mg paste air fuel cells and the output voltage and current of the cells were measured. The observed output voltage was 1.4 V when they were connected to a low load, which is the same as conventional Mg air cells. Metal oxides were reduced with high efficiency and at a noticeably low cost by using lasers generated from solar energy. This makes it possible to recycle Mg plates. The new recyclable Mg paste air fuel cells are expected to become common power supplies with high-energy density and high output power.