New discovery makes fast-charging, better performing lithium-ion batteries possible

New discovery makes fast-charging, better performing lithium-ion batteries possible
Materials research -- published in Nature Communications -- makes possible lithium-ion batteries that can charge in a matter of minutes but still operate at a high capacity. Credit: Rensselaer Polytechnic Institute

Creating a lithium-ion battery that can charge in a matter of minutes but still operate at a high capacity is possible, according to research from Rensselaer Polytechnic Institute just published in Nature Communications. This development has the potential to improve battery performance for consumer electronics, solar grid storage, and electric vehicles.

A lithium-ion battery charges and discharges as lithium ions move between two electrodes, called an anode and a cathode. In a traditional lithium-ion battery, the anode is made of graphite, while the cathode is composed of lithium cobalt oxide.

These materials perform well together, which is why have become increasingly popular, but researchers at Rensselaer believe the function can be enhanced further.

"The way to make batteries better is to improve the used for the electrodes," said Nikhil Koratkar, professor of mechanical, aerospace, and at Rensselaer, and corresponding author of the paper. "What we are trying to do is make lithium-ion technology even better in performance."

Koratkar's extensive research into nanotechnology and energy storage has placed him among the most highly cited researchers in the world. In this most recent work, Koratkar and his team improved performance by substituting cobalt oxide with vanadium disulfide (VS2).

"It gives you higher energy density, because it's light. And it gives you faster charging capability, because it's highly conductive. From those points of view, we were attracted to this material," said Koratkar, who is also a professor in the Department of Materials Science and Engineering.

Excitement surrounding the potential of VS2 has been growing in recent years, but until now, Koratkar said, researchers had been challenged by its instability—a characteristic that would lead to short battery life. The Rensselaer researchers not only established why that instability was happening, but also developed a way to combat it.

The team, which also included Vincent Meunier, head of the Department of Physics, Applied Physics, and Astronomy, and others, determined that lithium insertion caused an asymmetry in the spacing between vanadium atoms, known as Peierls distortion, which was responsible for the breakup of the VS2 flakes. They discovered that covering the flakes with a nanolayered coating of titanium disulfide (TiS2)—a material that does not Peierls distort—would stabilize the VS2 flakes and improve their performance within the battery.

"This was new. People hadn't realized this was the underlying cause," Koratkar said. "The TiS2 coating acts as a buffer layer. It holds the VS2 material together, providing mechanical support."

Once that problem was solved, the team found that the VS2-TiS2 electrodes could operate at a high specific capacity, or store a lot of charge per unit mass. Koratkar said that vanadium and sulfur's small size and weight allow them to deliver a high capacity and energy density. Their would also contribute to a compact .

When charging was done more quickly, Koratkar said, the capacity didn't dip as significantly as it often does with other electrodes. The electrodes were able to maintain a reasonable capacity because, unlike cobalt oxide, the VS2-TiS2 material is electrically conductive.

Koratkar sees multiple applications for this discovery in improving car batteries, power for portable electronics, and solar energy storage where high is important, but increased charging speed would also be attractive.


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Journal information: Nature Communications

Citation: New discovery makes fast-charging, better performing lithium-ion batteries possible (2019, April 16) retrieved 22 April 2019 from https://phys.org/news/2019-04-discovery-fast-charging-lithium-ion-batteries.html
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Apr 16, 2019
Provisionally good news, as charging time is one of the three prime hurdles for electric cars to become practical and widely adopted.

Apr 16, 2019
So I switched to an EV, and I can't really say that charging time is an issue at all (neither on short trips nor on longer ones). The range is in the region where you take a break anyways. If I take a 20 minute break I don't care if my car fills up in 5 minutes at a pump or charges the full 20 (actually the latter is a lot less hassle. You plug in; leave; come back; unplug. With an ICE I have to stay at the pump; go pay; and find an extra parking space afterwards if I want to take my break).

Most trips are well below the maximum range, so you actually have a lot LESS stays at fueling/charging stations than you did before. Charging at home doesn't take up any of your own time

That's the point I feel a lot of people don't get: The time your CAR takes to load up on energy - be it fuel or power - is irrelevant. It's the time that YOU invest in that process that's relevant.

Apr 16, 2019
Vanadium is not very abundant, and it's already in short supply for making different metal alloys for tools and machine parts. If you start using it for batteries as well, the price is going to skyrocket.

. Charging at home doesn't take up any of your own time


I live on the 7th floor. How do I get the car up to my apartment so I can charge at home?

Second question, where can I find an electric car that costs between 4000 - 7000 €/$/£ and goes for 400-600 km per charge?

Apr 16, 2019
The time your CAR takes to load up on energy - be it fuel or power - is irrelevant.


It becomes very relevant if your battery is empty and you need to get going somewhere.

That would be the case for example, if you wake up in the morning and find that you forgot to plug in last night, someone else used the car and didn't plug in, some wise guy unplugged it out of vandalism, or there has been a power fault that stopped the vehicle's charger, or the breaker tripped, or the car didn't charge up during the night for any other reason.

That's when you'd be glad to have a bigger battery with power in reserve, or the ability to charge up at the nearest service station in five minutes.

Apr 16, 2019
Most trips are well below the maximum range


Maximum range when new, or maximum range when the battery is old?

Don't forget you lose up to a third of the range as the vehicle ages. For a car with 150 km range when new, it fades to 100 km when old, and depending on the weather and local climate you can lose another half of the range. Worst case it goes from 150 km to 50 km which for a round trip means the furthest you can go and still get back is 25 km (16 mi). That's terrible.

And then you have to define what "most trips" means. Let's say 95% of trips - you'd still expect to see 18 days a year - more than once a month - when you have to go "Oh, I can't drive my expensive EV because it just doesn't go far enough".

Apr 16, 2019

"Second question, where can I find an electric car that costs between 4000 - 7000 €/$/£ and goes for 400-600 km per charge?"

@Eikka- Since the average price of a new car was $35,300 in 2018, you are going to have to settle for a very used (or flimsy cheap) car for $4000 to $7000. It will be quite a few years before you can get a decent Tesla or Bolt in this price range. So it is lucky for you that you intend to be a late adopter of electric vehicles.

Apr 17, 2019
4k-7k and 400-600km per charge are red herring requirements. (Because Eikka is too stupid to understand the fundamental difference between an ICE car and an EV..or just willfully obtuse in order to further his weird Luddite agenda.)

a) No one needs 600km range. No one. No one drives such a range without a pause - and you can easily charge up during a pause. Realistically you need 300km range. Tops.
b) 4k-7k is meaningless because an EV saves you a lot of money compared to an ICE car. If you want an EV that AS PRICEY as a 4k-7k ICE car (i.e. one that costs you the same over the lifetime of a car) you should be looking for a 19k-22k used EV (which are out there)

Apr 19, 2019
Most trips are well below the maximum range


Maximum range when new, or maximum range when the battery is old?

At 200.000 km in a Prius and the battery is still fine, it hasn't lost anything noticeable.

Many reports from Tesla drivers that their battery range loss after a lot of driving is negligible.

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