19 Jun 2020 14:32 IST

Look beyond lithium for powerful batteries

A promising alternative to the rare element is sodium, especially given its abundant availability

Lithium has become a household name today, thanks to its somewhat recently-discovered, extensive use in battery manufacture. Lithium-ion batteries (Li-ion) are now used in cellphones, laptops and even in battery packs used to drive vehicles.

There is good reason why the world loves this element. It is the lightest of all metals and is, by the way, the third lightest of all elements in the universe, after hydrogen and helium. This means that the batteries you make with lithium are light. They can also pack a lot of energy, and packing energy is what energy storage is all about.

Here are the numbers. A regular nickel-cadmium cell, which is the most commonly used ‘re-chargeable’ cell, can pack between 40 and 60 watt-hour per kg of nickel cadmium. (This is written as 60 W.hr/kg.) The lithium-ion battery can hold 180 W.hr/kg to 260 W.hr/kg, depending on which other element the lithium is combined with. (The most common is lithium-cobalt, but you can also have lithium-titanium oxide, lithium-nickel-manganese, etc. These are called battery ‘chemistries’.)

Of course, these are nothing compared with regular automotive fuels. Petrol, for instance, can hold 12,700 W.hr/kg — but then, we are talking about batteries here.

The flip side

So, lithium is fantastic, but like most things in the world, nothing is all good. Lithium’s flip side is that it is not available in abundance across all regions of the earth. A few lucky countries have lithium deposits, usually under salt flats. Most of these lucky countries are in South America. China has moved in swiftly and has extraction rights in many mines. (By the way, there is a salt flat in the disputed Aksai Chin area and, who knows, there could be lithium deposits under it – which would make this piece of Indian land in Chinese hands, very valuable.) So, access to lithium is limited. Also, if you go in for the best lithium chemistry — lithium cobalt — there is a bigger problem because cobalt is even rarer. Most of it is in the Democratic Republic of Congo, and China has already moved in there.

And lithium has another problem. It heats up quickly and often explodes. You may remember that some time back some airlines had banned passengers from carrying Samsung Note 7 because the batteries in the phone often exploded.

Well, sigh, no matter how much you love lithium, all this means you need to look for alternatives.

A viable alternative

The world has, indeed, been looking for alternatives for a while now. There are many who are toying with different chemistries — a professor in IIT-Madras, Dr S Ramaprabhu, has come up with an iron-ion battery, but the most promising seems to be sodium-ion.

Let’s call it, fancifully, like a Robert Ludlum novel: “The Sodium Alternative”.

Sodium chemistries can carry much less energy than lithium, though researchers are gnashing their teeth and yanking up the numbers slowly. The best you can get today is 160 W.hr/kg. This means that for the same amount of work that a Li-ion battery would do, you need a much bigger Na-ion battery. Imagine putting a heavy battery load on the truck. The battery would not only carry the truck’s load, but also itself.

That rather rules out The Sodium Alternative, doesn’t it? Not really. This is primarily because sodium is available abundantly, and everywhere. You can potentially extract sodium from sea water — only with today’s technologies, it is not economical. Nevertheless, sodium availability is not a problem. It is also much cheaper than lithium. And, weight does not matter for non-transport application. You could have a large battery system in a container attached to the electricity grid, which stores power for release when needed.

So, everybody is working up sodium to challenge lithium. This is where it gets interesting. India is not lagging behind. Indian research into sodium battery technology is on par with anywhere else in the world. Various IITs and laboratories like the Central Electro Chemical Research Institute (CECRI) have done some good work. In fact, CECRI and IIT-Bombay have developed complete cells (batteries are collections of cells).

The problem is, how to go forward from here.

Not enough ‘scienterpreneurs’

Scientists generally consider their work done when they invent or discover something. Then their mind goes into how to get their work published in a high-impact-factor scientific journal which could get them recognition. The more a scientist’s paper is quoted by others, the higher goes his value. Very few scientists think of making their invention a commercial product and those who do, just tie-up with an industry partner and trust in luck. We do not have a class of ‘scienterpreneurs’.

So, it falls upon industry to pick up potential money-making inventions and convert them into marketable products. In this area, Indian industry has proved to be extremely risk-shy. Taking a freshly minted sodium-ion battery technology to mass production would call for some risk-investments. Which Indian company is willing to put down, say, ₹100 crore, into making a product, which, if clicks, could earn billions? All the industry would do is to ask government to provide risk-finance, even though entrepreneurship is all about taking studied bets.

In the past, India has similarly been on par with the world in terms of research, but missed out in manufacture. Semiconductors is a good example. Today, India does not have a single semiconductor fab — we lost out to China and Taiwan in this area.

We also missed the lithium battery revolution. Now, The Sodium Alternative dangles tantalisingly before us. Will India seize the opportunity to become a world leader in sodium-ion technology? Well, no harm in hoping for the best.

Recommended for you