High Energy and High Power Electrically Rechargeable Zinc-Air Battery

Zinc air batteries use very cheap raw materials (Zinc, Carbon, Potassium Hydroxide) with material costs less than 10€/kWh. The fact that they are water based batteries also makes them much safer and they use environmentally benign and recyclable materials. There is no possibility of thermal runaway or fire either. Zinc-air batteries are therefore an interesting option for the electric vehicle, but also for lower cost stationary storage.

High energy density zinc-air batteries are already on the market with energy densities above 400 Wh/kg but they are not rechargeable. The technology to make zinc-air batteries on an industrial scale therefore already exists. The challenge now is to be able to make zinc-air batteries rechargeable.

Attempts to develop such a battery have failed due to the poor reversibility of the air electrode and due to the formation of zinc dendrites during charge. By using 3D electrode structures and a protected air electrode, an electrically rechargeable zinc-air battery has been developed which has solved these problems and which has high cycle efficiencies.

One of the disadvantages of metal-air batteries is their poor discharge power performance compared to Lithium-ion batteries. The culprit is the air electrode, the zinc electrode is not limited on discharge. Oxygen reduction is a multi-electron reaction with slow kinetics. The reaction is further impaired by the low concentration of the active material (oxygen from the air) and the low molar density of a gaseous reactant.

The addition of a second high power cathode has solved this problem and has brought very interesting power and energy performances to our zinc-air battery.

High energy densities have also been achieved using zinc electrodes with very high loadings, up to 630 mAh/cm².

These zinc-air cells are tested under standard cycling conditions, but also using normalised electric vehicle driving cycles.