Metal-air Batteries

Subject – Science and Tech

Context – The need for India to grow out of (Chinese-dominated) lithium for energy storage is well recognised.

Concept –

Lithium is scarce, less safe, and lithium-ion has energy limitations.
Metal-air batteries, which have a metal anode (electron giver) and atmospheric oxygen as the cathode (electron acceptor), have been attractive because you can use cheaper and easily available metals such as sodium, zinc, iron, aluminium, magnesium and calcium. Of these, zinc and aluminium are ahead in the race, followed by sodium and iron.
For range, calculated in kWhr/kg, metal-air batteries are first class — they beat lithium-ion (Li-ion) blue (though lithium-air is even better).
Since the voltage of metal-air batteries is typically less than that of Li-ion, you might need more cells, but the cells weigh much less because they have air for cathode.
The biggest challenge is over rechargeability.The ‘parasitic hydrogen evolution’ at the anode corrodes it and affects the performance of the electrolyte; there is also the formation of spikes (dendrites) on the metal anode.
Among the other issues with metal-air is the reaction of atmospheric carbon dioxide with the electrolyte to form carbonates and the erosion of the catalyst coated on the electrodes, but none of these is considered insurmountable.
As such, metal-air batteries are today feasible enough for industry to start jumping into it.

To know about Li-ion Batteries, please click here.