Zinc-Air Fuel Cells

Rechargeable zinc-air fuel cell

Ten years ago a rechargeable zinc-air battery was considered to be the most promising storage device for energy demanding applications. The specific of construction is an air electrode, which is similar to that of a fuel cell. This means the zinc-air battery includes only one zinc anode while the cathode is just a thin layer of a catalyst that assures the reduction of air to water.

Based on this design, the theoretical energy density of the zinc-air battery is equivalent to the specific energy of the zinc electrode 7026Wh/L. The zinc-air battery is the single power supply, which is inherently protected from a short circuit because the current is limited by the diffusion of air to the air electrode. The zinc-air battery is the cheapest storage device if the air electrode catalyst does not include noble metals. With all these benefits in mind about 15 companies, research organizations and university groups tried to commercialize rechargeable zinc-air batteries between 2009 and 2014.

Rechargeable nickel-zinc batteries with rechargeabke zinc cartrudges for energy storage and solar-plus-storage applications. Battery grade nickel hydroxide.

Panisolar is one of several companies that were successful to demonstrate the rechargeable zinc-air batteries/fuel cells. Several ideas helped to assure performance. The three electrode design split the rechargeable air electrode into oxygen reduction and oxygen evolution electrodes. The replaceable zinc cartridge was used to increase the battery cycle life. Also, a metal free air electrode catalyst based on a carbon lattice doped with nitrogen was developed. Its success was also assured by a new current collector to the zinc electrode that contributed to the battery stability.

The zinc-air battery can be embodied both as a conventional rechargeable battery, and as a rechargeable fuel cell. The latter uses replaceable zinc cartridge as a fuel. The device can be recharged by the mechanical replacement of the zinc cartridges; that means no access to electricity is needed, and the power source can be used during blackouts. At a later time (or place,) when electricity supply resumes, the zinc electrodes can be regenerated by electrochemical reduction in a supplementary electrochemical cell with high efficiency and at low cost.