Scientists at the University of Pennsylvania Electrochemical Engine Center have invented a self heating lithium ion battery that dramatically improves cold weather performance. It uses a thin foil made of nickel that surrounds the battery and draws its power from it. The scientists choose nickel for their hearing blanket because it is inexpensive. They say their system increases the weight of the battery by only 1.5% and adds just 4% to its cost.
In a study published in the journal Nature on January 20, lead researcher Chao-Yang Wang said “It is a long standing problem that batteries do not perform well at subzero temperatures. This may not be an issue for phones and laptops, but is a huge barrier for electric vehicles, drones, outdoor robots and space applications.” An EV battery may lose 40% of its range in sub-zero temperatures. A cold battery also may not be able to take advantage of electricity made by regenerative braking systems. Range loss in cold weather means manufacturers have to equip their EVs with larger, costlier batteries to compensate.
“We don’t want electric cars to lose 40 to 50 percent of their cruise range in frigid weather as reported by the American Automobile Association and we don’t want the cold weather to exacerbate range anxiety,” said Wang. “In cold winters, range anxiety is the last thing we need.”
Based on patents held by EC Power, a start up company where Professor Wang is the chief technical officer, the nickel foil system can heat itself from -20 to 0 degrees Celsius within 20 seconds and from -30 to 0 degrees Celsius in 30 seconds. It uses between 4 and 6 percent of the battery’s capacity to heat up, which is considerably less than the power loss most batteries suffer in below freezing conditions. A temperature sensitive switch on the outside of the battery turns the current needed to heat the battery on and off, according to Electric Car Report.
“Next we would like to broaden the work to a new paradigm called SmartBattery,” said Wang. “We think we can use similar structures or principles to actively regulate the battery’s safety, performance and life.”