Temperature consistency–oriented rapid heating strategy combining pulsed operation and external thermal management for lithium-ion batteries

The poor performance of lithium-ion batteries (LIBs) at low temperatures restricts their application in electric vehicles (EVs), and existing preheating methods might lead to insufficient temperature consistency and heating rates. This study proposes an innovative method that integrates pulsed operation and external liquid circulation to heat LIBs. Experiments are performed on a LIB module under different conditions; key parameters of the proposed method are regarded as indexes to evaluate its heating effect. Furthermore, its temperature consistency is studied by both experiments and simulations. In particular, inconsistencies of the state of charge (SOC) and internal resistance among cells, and the heat preservation are examined by experiments. Among all parameters, the cooling plate layout and coolant temperature are key factors. Under inconsistent conditions, the increase in the temperature difference is less than 2 °C, even when the internal resistance of peripheral cells is 50% higher than that of other cells. For on-board applications with better heat preservation, the temperature difference can be maintained within 1 °C during heating from − 20 °C to 6 °C in 300 s, and the temperature consistency is 11 times better than that of pulsed heating only. Overall, the proposed combined heating method achieves high heating rates while ensuring excellent temperature consistency and robust performance for practical applications of EV packs. It offers significant prospects in addressing the cell degradation and potential safety hazards of LIBs at low temperatures.