Truck major Ashok Leyland and Hindustan Zinc have (separately) joined hands with IIT-Madras in the technology institutes endeavour to develop a Zinc air battery.

While Lithium-ion batteries are the darling of the energy storage industry today, they pose challenges such as concentration of raw material source with a handful of countries, high charging time and safety issues in hot climates. (Technologies for fast charging are coming up, but they are expensive.) Therefore, a worldwide search is under way for a good alternative. Sodium-ion, iron-ion and metal air batteries are the emerging candidates.

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Dr Aravind Kumar Chandiran of the Department of Chemical Engineering, IIT Madras, heads a team that is developing a Zinc air battery. His target is two-fold: a battery whose cost per kWhr is at least half of the conventional Lithium-ion batteries and one that re-charges really fast.

Talking to BusinessLine, Dr Chandiran said that while Ashok Leyland is the industry partner under the government of Indias IMPRINT-2 programme (under which the research has been granted 1.5 crore), Hindustan Zinc is a separate funding arrangement with different deliverables. Hindustan Zincs interest is, obviously, to create a market for Zinc.

Dr Chandiran said that today a Lithium-ion battery costs $270-300 per kWhr (unless contracted for huge quantities, when the price could come down to $220 a kWhr). In contrast, a Zinc air battery produced today would cost $150 a kWhr; if produced on the same scale as Lithium-ion batteries, the costs would come down to $30-40 a kWhr, he said.

At the heart of the battery is the Zinc anode which can be taken out once the battery discharges its power, and replaced. Like pulling a cassette out and inserting another, says Chandiran. The cathode of the battery is, as for metal air batteries, air. Zinc reacts with the Oxygen in the air to deliver electricity, and becomes Zinc oxide. In an external contrivance, which could be solar-powered, Oxygen is kicked out of the Zinc oxide and the metal is won back a process called electrowinning.

Chandirans team is working on a design to develop battery packs of 15Ah and ~24V that are mechanically rechargeable and run a 5 kW drive motor. The novelty lies in the design of battery pack for maximum power and ultra fast electrode replacement, he says.

Of course, it is theoretically possible to recharge the battery onboard the vehicle, but it calls for a different research at a more fundamental level. It involves developing a bi-functional catalyst for two activities discharging and recharging known in chemistry as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This is also an area that Dr Chandiran is working on, but is not connected to the Zn air battery project.

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Meanwhile, another research is going on IIT Madras to develop a new type of anode for the Lithium-ion batteries. The conventional anode used is graphite which, according to Prof Prathap Haridoss, has its own practical issues such as lower capacity and limited fast-charging capability.

In a recent paper published in Advanced Energy Materials, an international scientific journal, Dr Haridoss and his team (which included Dr Raghavan Gopalan of IIT Madras, Dr Abhijit Chatterjee of IIT Bombay, Dr Raju Prakash, Dr Vallabha Rao Rikka and Dr Sumit Ranjan Sahu of International Advanced Research Center,) have mentioned their development of a composite made of molybdenum trioxide and carbon nanohorns. Carbon nanohorns are nano materials, just like nanotubes and graphene.

The battery developed using this new anode material will have about three times the energy density as conventional Lithium-ion batteries, Prof Haridoss told BusinessLine. The anode will cost about the same as graphite.

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Ashok Leyland, Hindustan Zinc team up with IIT-M to develop Zinc air battery - BusinessLine