Owners of electric vehicles may soon be able to get into a gas station, turn on their car, go to the toilet, grab a cup of coffee, and leave in 10 minutes with a fully charged battery, according to a team of engineers.
"We have demonstrated that we can charge an electric vehicle in ten minutes for a range of 200 to 300 miles," says Chao-Yan Wang, William E. Difenderfer Chair of Mechanical Engineer, Professor of Chemical Engineering and Professor of Materials Science and Engineering and director of the Pen Center for Electrochemical Engines. "And we can do that by maintaining 2,500 charging cycles or the equivalent of traveling half a million miles."
"Fast charging is the key to ensuring widespread introduction of electric vehicles." – Chao-Yang Wang
Lithium ion batteries break down when charged quickly at ambient temperatures below 50 degrees Fahrenheit, as lithium ions are introduced smoothly into carbon anodes, lithium is deposited in spikes on the surface of the anode. This lithium coating reduces the capacity of the cell, but it can also cause electrical spikes and dangerous battery conditions.
Batteries heated above the lithium coating threshold, whether by external or internal heating, will not show lithium coating.
Researchers have previously designed their battery to be charged at 50 degrees F for 15 minutes. Charging at higher temperatures would be more efficient, but long periods of high heat also deplete the batteries.
"Fast charging is the key to making widespread use of electric vehicles," Wang says.
Wang and his team realize that if the batteries could heat up to 140 degrees F in just 10 minutes and then cool quickly to ambient temperature, lithium spikes would not form and thermal degradation of the battery would also be absent to arise. They report their results in the October 30, 2019, issue of Joule .
"Bringing this battery to the final 60 degrees Celsius (140 degrees F) is prohibited in the battery arena," said Wang, "It is too high and is considered to be a material hazard and would dramatically reduce battery life."
"We have demonstrated that we can charge an electric vehicle in ten minutes for a range of 200 to 300 miles, and we can do that maintaining 2500 charging cycles or the equivalent of traveling half a million miles. "- Chao-Yang Wang
The rapid cooling of the battery will be accomplished with the help of a cooling system designed in the car, Wang explained. The large difference of 140 degrees to about 75 degrees F will also help increase the cooling rate.
"The 10-minute trend is for the future and is essential for the adoption of electric vehicles because it solves range anxiety,"
Adding range anxiety reduction – fear of running out of power without recharging opportunity or time – will be, according to Reuters, the creation of 2,800 charging stations in the US, funded by more than $ 2 billion in damages paid by Volkswagen after allowing it to cheat on diesel emissions. These charging stations will have 500 seats.
The self-heating battery uses a thin nickel foil with one end attached to the negative terminal and the other extending beyond the cell to create a third terminal. A temperature sensor attached to a switch causes the electrons to pass through the nickel foil to complete the circuit. This quickly heats the nickel foil by steadily heating it and warming the inside of the battery.
Reference: "Asymmetric temperature modulation for extremely fast charging of lithium-ion batteries" by Xiao-Guang Yang, Teng Liu, Yue Gao, Shanhai Ge, Yongjun Leng, Donghai Wang and Chao-Yang Wang, October 30, 2019, Joule .
DOI: 10.1016 / j.joule.2019.09.021
Also working on this project from Penn State are Xiao-Guang Yang, Research Assistant; Ten Liu, PhD student; Yue Gao, PhD; Shanghai Ge, research assistant; Yongyun Lang, research assistant; and Donghai Wang, a professor, from the Department of Mechanical Engineering.
The US Department of Energy supported this work.