To charge an electric car in 10 minutes, just heat the battery
Plug your running-on-empty electric vehicle into a charging station, stroll inside for a cup of coffee, commiserate with the cashier about the weather, then head back to your car. You're all charged up for another three or four hours of driving.
Researchers at Penn State University say they've figured out how to make such a quick charge possible.
"We demonstrated that we can charge an electrical vehicle in 10 minutes for a 200 to 300 mile range," said Chao-Yang Wang, director of the Electrochemical Engine Center at Penn State.
The rapid charge doesn't fry the battery, either. "We can do this maintaining 2,500 charging cycles, or the equivalent of half a million miles of travel," Wang said. He was quoted in a Penn State news release.
What's the secret? Heating the battery to 60°C (140°F). (Note: PLEASE don't try this at home. The Penn State researchers developed a special battery.)
Electric vehicles use lithium-ion batteries. Rapid charging normally degrades them, depositing lithium spikes on the anodes that not only reduce capacity but also can make the batteries unsafe.
Heating the battery solves that problem. Unfortunately, high temperatures also degrade batteries.
"Taking this battery to the extreme of 60 degrees Celsius is forbidden in the battery arena," Wang said. "It is too high and considered a danger to the materials, and would shorten battery life drastically."
However, the researchers learned, if you heat the battery only briefly, then immediately cool it before you start drawing power from it, the battery functions just fine.
Wang and his team developed a self-heating battery that also rapidly cools itself back down to the ambient temperature. They published an article about their work on October 30 in the journal Joule; you can read it here.
For electric vehicles to go mainstream in the US, we need a national network of charging stations, and the charging needs to happen quickly.
Various entities are working on the first problem. Notably, a partnership called Electrify America plans to spend $2 billion over the next decade building fast charging stations across the country. Volkswagen is supplying the money as part of a settlement relating to its emissions test cheating scandal.
This Penn State research could take care of the second need. "Fast charging," Wang said, "is the key to enabling widespread introduction of electric vehicles."