Improving temperature uniformity of a lithium-ion battery by intermittent heating method in cold climate

The charge-discharge performances of lithium-ion batteries in hybrid electric vehicles (HEVs) and pure electric vehicles (EVs) decline rapidly at low temperatures. Many heating methods have been proposed to improve low-temperature performance, but these heating methods require long heating time and lithium-ion batteries at the end of heating have poor temperature uniformity. Recently, a self-heating lithium-ion battery (SHLB) has been proposed to recover charge-discharge performances of lithium-ion batteries at low temperature in short time. However, temperature uniformity of a lithium-ion battery heated by SHLB is also poor. A three-dimension heating finite element model is established in this work to analyze temperature gradient of a lithium-ion battery heated by SHLB heating method in detail, and intermittent SHLB heating method is proposed. For the intermittent SHLB heating method, a lithium-ion battery is heated for some time and stopped heating for some time instead of continuing heating. Through simulation analysis and comparison, heating for 0.1 s and stopping heating for 0.3 s is proposed to decrease the temperature gradient, and temperature difference is decreased from 10-11 K to 2-3 K.