The self-heating battery uses a thin nickel foil with one end attached to the negative terminal and the other extending outside the cell to create a third terminal. A temperature sensor attached to a switch causes electrons to flow through the nickel foil to complete the circuit. When charging, this rapidly heats up the nickel foil through resistance heating and warms the inside of the battery.

According to the researchers, rapid heating and subsequent cooling do not cause lithium spikes, which means that heat degradation of the battery does not occur.

Lithium-ion batteries degrade when rapidly charged at ambient temperatures under 50 degrees Fahrenheit because, rather than the lithium ions smoothly being inserted into the carbon anodes, the lithium deposits in spikes on the anode surface. This lithium plating reduces cell capacity, but also can cause electrical spikes and unsafe battery conditions.

However, the technique proposed by Chao-Yang Wang, William E. Diefenderfer Chair of mechanical engineering, professor of chemical engineering and professor of materials science and engineering, and director of the Electrochemical Engine Center at Penn State and his colleagues entails that following the rapid heating, immediate cooling is the key. The latter can be accomplished using a cooling system designed into the car.

“We demonstrated that we can charge an electric vehicle in ten minutes for a 200 to 300-mile range,” Wang said. “And we can do this maintaining 2,500 charging cycles or the equivalent of half a million miles of travel.”

In the scientist’s view, fast charging is extremely important to promote the widespread introduction of electric vehicles.