In a significant development for the electric mobility and the larger stationary battery storage ecosystem in India, researchers at the Indian Institute of Technology, Madras, are developing mechanically-rechargeable zinc-air batteries as an alternative to lithium-ion (Li-ion) batteries.
After filing for patents, these researchers under Dr Aravind Kumar Chandiran, assistant professor at the Department of Chemical Engineering, IIT-Madras, are collaborating with major industries to develop these zinc-air batteries. Compared to existing Li-ion batteries, the researchers at IIT-Madras claim that their zinc air counterparts have a long shelf life, are cheaper, safer and can be used in two and three-wheeler electric vehicles (EVs).
“In our laboratory at IIT-Madras, we have invented low-cost and safe metal-air battery systems and that metal is based on zinc. These metal-air batteries are nearly three times cheaper even at the scale at which we have developed them. Also, the technology has been developed in-house. The country has abundant amounts of zinc, making it unique. India will own the technology and have the safest technology for its next-generation energy storage systems. These batteries can potentially be used in EVs for low-powered applications like two-wheelers and three-wheelers and also stationary energy storage systems,” says Dr Chandiran.
“Speaking of stationary energy storage, solar energy is available during the daytime, and that energy peaks around midday and weans off towards the end of the day. We use batteries to store that excess energy available at mid-day. So far, we have options based on lead-acid or lithium-ion battery technologies. But India doesn’t own any of these technologies, so we will have to move to our in-house technologies with resources available domestically. Zinc is found abundantly in India and we are also one of its largest producers,” he adds.
Powering Zinc-Air Batteries
Akin to petrol stations for IC-engine vehicles, the researchers are mooting separate ‘Zinc Recharge Stations’. Based on ‘Battery-Swapping’ technology, EV users can swap used ‘zinc cassettes’ of the battery with fully-charged ‘zinc cassettes’ at these ‘Zinc recharge stations.’
Elaborating on this aspect, Dr Chandiran says, “This is a major advantage of the zinc-air batteries as currently the only option available with the lithium-ion batteries is that the entire used battery pack has to be removed and be swapped with a complete lithium-ion battery pack. This results in double the capital investment in the case of lithium-ion batteries.”
In other words, zinc-air batteries require only anode swapping and not the entire battery, like in the case of Li-ion.
Advantages of Zinc-Air Batteries
The team at IIT Madras started researching and developing these Zinc Air batteries around three years ago. “The motivation was quite simple. It was to develop in-house technologies that offer low-cost energy storage and safe batteries,” explains Dr Chandiran.
As stated above, Zinc is widely available in India. This naturally would reduce dependence on countries like China or South Korea for Li-ion battery cells and thus lessen imports.
Also, as stated earlier, zinc is cheaper than Li-ion batteries. Researchers note that while Li-ion batteries cost USD 200 to 250 a KWh, zinc-air batteries cost around USD 150 KWh. With wider usage, the price is expected to come below USD 100 KWh. They add that these batteries are water-based, have a longer shelf life and good turnaround efficiency.
“Zinc-air batteries can offer better range. We are still testing their cycle life, but expect them to serve for a couple of thousand cycles. They don’t require a dry atmosphere to fabricate batteries like Li-ion batteries. Zinc-air batteries can also be fabricated in ambient conditions, and so there is less investment in CAPEX. They are yet to be tested on the road,” explains Dr Chandiran.
“We are working with OEMs and expect to put them on the road after a couple of tests. Optimistically, we would require two years before we see a fruitful outcome on the road, as we would like to do rigorous testing before we employ them in vehicles,” he adds.
Besides zinc-air batteries, there are other alternatives that are being considered for the Indian EV market. For example, there is sodium-ion, which experts believe is “cheaper than lithium-ion cells by about 30-40%”. Besides cheaper costs, there are other advantages associated with sodium-ion like its availability in India, battery capacity, and environmental impact.
In developing zinc-air batteries, researchers at IIT-Madras have offered India another option for self-sufficiency in fulfilling its electric mobility and stationary battery storage requirements.
Source: IIT-M / Better India