Scientists developing high-performing battery for electric cars and drones

A new energy-dense battery made from lithium-oxygen could take electric cars and drones to the next level.

tesla model s japan trimmed

The Tesla Model S

Credit: Creative Commons Lic.

Lithium-oxygen batteries will be 10 times as energy-dense as the lithium-ion technology we're using today. It will be significantly lighter than anything we've seen to date.

Why the obsession with weight reduction in batteries?

Weight is an issue in vehicle battery chemistry because the heavier a vehicle is, the more power you need to propel it. Which means you need more batteries. That results in more weight, and it becomes an ever-decreasing circle.

Diminishing returns

As things stand now, you can't just keep adding more powerful batteries, because they add weight and size, and actually result in that diminishing return.

An example of this problem can be found in drone design—something we'll all be doing soon.

You'd think a larger-capacity 16 Amp hours (Ah) battery would provide more flight time than a 10 Ah battery. With that battery, more amps are deliverable in a period. However, it doesn't work out that way when you perform the calculations.

Working harder

The 16 Ah battery weighs 1,290 grams, and the 10 Ah battery only 804 grams. Add those weights to the aerial vehicle, along with some other calculations, and you get 17 minutes of flight time with the smaller battery and 15 minutes with the larger.

The heavier battery is causing the drone to work harder to stay off the ground, despite the greater capacity of the power source.

And it's the same with electric cars—the heavier battery creates more work. A lighter battery will let the car go further on fewer charges.

Hence the excitement over the new battery chemistry. Anything that will reduce weight is the Holy Grail.

More efficient

Lithium-air, or lithium-oxygen batteries, will be 90% efficient and will be able to be recharged 2,000 times, according to an article on the Cambridge University website.

"Such a high energy density would be comparable to that of gasoline, and would enable an electric car with a battery that is a fifth the cost and a fifth the weight of those currently on the market," the article reads.

With that technology, you'd be able to drive from London to Edinburgh on one charge, the university says. London to Edinburgh is about 400 miles, roughly the same driving distance as Boston to the outer Washington, DC, suburbs.

In comparison, the range of a 2015 Tesla Model S electric automobile with 85kW-hr battery is only 265 miles, according to the U.S. Environmental Protection Agency.

Exploding batteries

It's not the first time that lithium-air has been attempted, but the Cambridge version appears less volatile, according to the scientists. One of the problems with new battery chemistries is that battery chemistry is energy, which can be volatile.

There's a reason airlines don't want the tech in the hold. It's easier to put out fires in the cabin.

Previous attempts at working demonstrators "have had low efficiency, poor rate performance, unwanted chemical reactions, and can only be cycled in pure oxygen," the researchers say.

Blowing up

And it has been unwanted chemical reactions that has been the scourge of new battery tech.

I've written about how researchers are trying to tame silicon battery technologies and stop them from exploding in "How a '70s technology is stopping smartphone progress…and why that might change soon."

The team says its air version, using lithium peroxide in its demonstration with graphene, is more stable and efficient.

They also think that lithium air chemistry will see less deterioration with age.

'Routes forward'

The scientists say that their chemistry is still 10 years away from production, but they think that their lab demonstration shows "routes forward towards a practical device," Professor Clare Grey of Cambridge's Department of Chemistry, the paper's senior author, said on the Cambridge University website.

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