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Electrode advances opens path to affordable and rechargeable zinc-air batteries

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STANFORD University scientists have created an advanced zinc-air battery which provides higher efficiency and durability than similar batteries made with costly catalysts.

Conventional lithium-ion batteries are set to be replaced by metal-air batteries, which have drastically higher theoretical energy density. However, previously developed metal-air batteries utilise expensive catalysts like platinum.

The creation of zinc-air batteries means there is now a technical and economically viable metal-air battery option.

Zinc-air batteries generate electricity by combining atmospheric oxygen and zinc metal in a liquid electrolyte, with a byproduct of zinc oxide. When the process is reversed during recharging, oxygen and zinc metal are regenerated.

Zinc metal is abundant and low-cost, and the aqueous electrolytes used in the battery are non-flammable, enhancing operational safety.

While non-rechargeable zinc-air batteries are now used in commercial medical and telecommunication applications, researchers were challenged with developing electrically rechargeable batteries.

To make rechargeable metal-air batteries, high-performance electrodes are necessary to catalyse the oxygen-reducing reaction during discharge and oxygen production during recharge.

The research team created new electrode catalysts made of cobalt oxide, a nickel-iron compound and carbon nanomaterials. The catalysts allowed the batteries to achieve record high-energy efficiency for a zinc-air battery, with a high specific energy density more than twice that of lithium-ion technology.

The novel battery also demonstrated good reversibility and stability during long charge and discharge cycles over several weeks, which bodes well for a future role in the development of practical, rechargeable zinc-air batteries.