IIT-Madras innovates zinc-air batteries to take on lithium-ion

For a long, owing to their versatility and life cycle, lithium-ion batteries have dominated the battery industry with a global market size close to $41.97 billion. Recently, with the entry of electric vehicles, rechargeable, affordable batteries have found an even bigger, growing market globally, especially in India.

A next-generation, low-cost, indigenous choice that makes the use of available resources and futuristic technology became the need of the hour. The quest has led a team of researchers at IIT-Madras to develop zinc-air batteries.

The batteries are safe for vehicles since they use water-based electrolytes and no flammables. The life cycle is longer whereas the mileage per kWh is the same as lithium-ion. The technology is currently undergoing trials. With indigenisation, these batteries are expected to be market-ready and for commercial use in three to five years.

“It is a fairly mature, safe choice that makes use of abundant resources of zinc available in India,” says Dr Aravind Kumar Chandiran, assistant professor, Department of Chemical Engineering, IIT-Madras, who has headed the team of researchers.

But the highlight of these batteries, notes Dr Chandiran, is that zinc-air can operate at low power with high energy. “In a given volume of the battery, the total energy stored is equal to or higher in zinc-air compared to lithium-ion systems. So it is ideal for two-wheelers and three-wheelers. Fabrication is done in ambient conditions and employs nearly all low-cost elements, so cost is very low,” he says.

However, the Indian market requirements are diverse. The EV market size in the country is currently valued at $220.1 million and is pegged to experience a growth rate of 94.4% annually between 2021-2030.

With such a high-volume demand, the zinc-air battery discovery has already fuelled a lot of interest from many automobile manufacturers. The research project that is funded by the IMPRINT programme by DST, and also partially funded by an automobile OEM team, is currently at TRL4 and will soon be proceeding to TRL5 and TRL6.

The research has not only provided a feasible alternative but also addressed some of the shortcomings of lithium-ion batteries the market has grappled with, so far. Unlike the replacement of whole battery packs in the case of used lithium-ion batteries, used zinc battery cassette packs can be removed and replaced with fully-charged ones at the ‘zinc recharge stations’, which are going to be put up across all user locations. Efforts are also on to recharge the cassette packs using solar energy.

Right now, at the patent filing stage, these batteries are focussed on the EV market in India and also the stationary storage devices market, including grid balancing. Of course, says Dr Chandiran, “The technology is universal and open to application anywhere across the world.”

However, the batteries have their own set of challenges too. The power of zinc-air is low compared to lithium-ion. So cars, which require high power cannot be powered by zinc-air and for the same reason, large-scale implementation is also difficult.

But zn-air will certainly add a spurt to battery market growth that was so far majorly attributed to the use of lithium-ion batteries. Though other new battery technologies such as sodium-ion, metal-air and solid-state comprise the market alternatives, Zn-air batteries signify a tremendous leap in the charging infrastructure for being green and economical and will aid the country’s target of 100% electrification by 2030.

“Since sun and wind are intermittent, we expect the low-cost zinc-air batteries to act as a significant energy storage system for assuring 100% green supply of energy for EVs and stationary storage systems. Tamil Nadu is one of the hottest spots for manufacturing companies. Zinc-air battery tech can be benefitted from this pro-manufacturing ambience in the state,” Dr Chandiran explains.