Engineers at Pennsylvania State University have developed a new lithium ion battery that can charge an electric vehicle in 10 minutes. The technology could offer electric cars an additional 200 miles of driving range, alleviating concerns of becoming stranded on long trips.
In order to encourage the adoption of electric vehicles by the average driver, electric vehicle makers have been trying to find ways to charge lithium ion batteries more quickly.
When the lithium ion batteries currently used in electric vehicles are charged at rapid speeds — quickly taking on 400 kilowatts of energy — they become vulnerable to lithium plating, the formation and growth of metallic lithium around the anode. Lithium plating diminishes the performance and shrinks the lifespan of lithium ion batteries.
Researchers at Penn State realized they could avoid this pitfall by charging batteries at elevated temperatures. Most batteries charge and discharge at the same temperature. In the lab, engineers charged batteries at a temperature of 60 degrees Celsius, or 140 degrees Fahrenheit. The batteries quickly cooled when discharged.
“In addition to fast charging, this design allows us to limit the battery’s exposure time to the elevated charge temperature, thus generating a very long cycle life,” Chao-Yang Wang, a mechanical engineer at Penn State, said in a news release. “The key is to realize rapid heating; otherwise, the battery will stay at elevated temperatures for too long, causing severe degradation.”
Wang and his colleagues described their new battery design this week in the journal Joule.
To heat the battery, Wang and his research partners outfitted a lithium ion battery with a self-heating nickel structure. The casing can preheat in 30 seconds and works to uniformly heat the battery. The higher temperature allows the battery to rapidly charge without triggering lithium plating.
In tests, researchers showed their hot-charging battery could last for 1,700 charge-discharge cycles without suffering degradation or performance loss.
“In the past, it was universally believed that lithium ion batteries should avoid operating at high temperatures due to the concern of accelerated side reactions,” said Wang. “This study suggests that the benefits of mitigated lithium plating at the elevated temperature with limited exposure time far outweigh the negative impact associated with exacerbated side reactions.”
Because the researchers built the new battery with all commercially available components, they estimate the technology is easily scalable. The researchers estimate the battery will be cheaper to produce, as the nickel structure eliminates the need for external heaters.
“We are working to charge an energy-dense electric vehicle battery in five minutes without damaging it,” Wang said. “This will require highly stable electrolytes and active materials in addition to the self-heating structure we have invented.”