Penn State Team Develops Self-Heating Lithium-ion Battery

Researchers at Penn State University and its new-energy spinoff EC Power LLC say they have developed a lithium-ion battery structure capable of heating itself without external devices or electrolyte additives at temperatures below freezing.

The so-called “all-climate” battery cell promises to improve the performance of hybrid and all-electric vehicles in cold weather. The researchers detailed the technology in the science journal Nature.

The new battery has a microscopic nickel foil attached to the negative terminal, with the other end of the foil extended 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.

Resistance heating rapidly heats the nickel foil and warms the inside of the battery. Once the battery temperature is above freezing, the switch turns off and electric current flows normally.

The technology allows the battery to warm itself from -20˚C to zero degrees within 20 seconds and from -30˚C to zero in 30 seconds while consuming less than 6% of cell capacity, according to the researchers. They say this allows for a more than 10 times improvement in power conservation over current lithium-ion batteries at extreme low temperatures, which will help extend EV driving range in such conditions.

EC Power expects further improvements will allow a -20˚C self-heating time to 5 seconds with 1% energy consumption by 2017.

The new battery weighs less than 2% more than traditional lithium-ion cells, according to the researchers. Costs are expected to be virtually the same.