Self-heating battery to beat winter woes for electric cars

Batteries of electric vehicles do not perform well at subzero temperatures. This long-standing problem can soon be a thing of the past as researchers have developed a new lithium-ion battery that self-heats if the temperature is below zero degree Celsius.

Conventional batteries at below freezing temperatures suffer severe power loss, which leads to slow charging in cold weather, the researchers said.
"It is a long standing problem that batteries do not perform well at subzero temperatures," said Chao-Yang Wang, professor at Pennsylvania State University in the US.

"This may not be an issue for phones and laptops, but is a huge barrier for electric vehicles, drones, outdoor robots and space applications," Wang noted. The all-climate battery developed by the team of researchers from Pennsylvania State University and EC Power, a company providing solutions for various power needs, weigh only 1.5 percent more than conventional batteries.

Described in the journal Nature, the all-climate battery uses a nickel foil of 50-micrometre thickness with one end attached to the negative terminal and the other extending outside the cell to create another terminal. A temperature sensor attached to a switch causes electrons to flow through the nickel foil to complete the circuit.

This rapidly heats up the nickel foil through resistance heating and warms the inside of the battery. Once the battery is at zero degree Celsius, the switch turns off and the electric current flows in the normal manner. While other materials could also serve as a resistance-heating element, nickel is low cost and works well, the researchers said.