As has been known for many decades, conventional batteries at below freezing temperatures suffer severe power loss, slow charging in cold weather, restricted regenerative breaking and reduction of vehicle cruise range by as much as 40 percent, leading to what is called “range anxiety” among owners of electric vehicles.
To solve this long-standing problem, a group of researchers from Penn State and EC Power, State College, has come up with a lithium-ion battery that self-heats whenever ambient temperature drops to 32 degrees Fahrenheit, or 0° C.
This could be a potential life-saver not only for environmentally-friendly transportation, but also for drones, outdoor robots and space equipment.
Relying on previous patent by EC Power, the researchers developed the all-climate battery to weigh only 1.5 percent more and cost only 0.04 percent of the base battery. They also designed it to go from -4 to 32 degree Fahrenheit within 20 seconds and from -22 to 32 degrees Fahrenheit in 30 seconds and consume only 3.8 and 5.5 percent of the cell’s capacity.
The new battery uses a 50-micrometres thick nickel foil with one end attached to the negative terminal and the other extending outside the cell to create a third terminal.
Even though other materials could serve as a resistance-heating element just as well as nickel, the latter is low-cost and works perfectly, noted study co-author Chao-Yang Wang who’s a Professor of Chemical Engineering and Director at Electrochemical Engine Centre.
As the temperature drops, a sensor triggers a switch that causes electrons to flow through the nickel foil to complete the circuit, thereby warming it up through resistance heating, which ends up raising the temperature of the battery itself.
Once the cell reaches 32 degrees Fahrenheit again, the switch automatically turns off and the electric current resumes to flow normally.
“Next we would like to broaden the work to a new paradigm called SmartBattery,” said Wang. “We think we can use similar structure or principles to actively regulate the battery’s safety, performance and life.”