Experimental study on liquid immersion preheating of lithium-ion batteries under low temperature environment

An experimental platform to examine the effects of single-phase immersion preheating on lithium-ion battery performance at low temperatures was set up in this study. The performance of lithium-ion batteries at low temperatures can be improved through immersion preheating. After preheating from −15 °C to 15 °C, the battery capacity can recover to over 80 % of its rated capacity. The three influencing factors are inlet flow rate, fluid temperature, and cell spacings. The inlet temperature exerts the most influence on the preheating performance. The warming rate can reach 1.63 °C/min at a temperature of 50 °C. While the increase in flow rate has less influence on the heating rate, it has a greater impact on the temperature difference between cells. The maximum temperature difference between cells can still be kept below 4 °C. The impact of spacing on the heating rate and temperature difference is minimal. The temperature difference can be controlled within 6 °C. Finally, it's important to note that immersion preheating consumes significant amount of energy. The energy consumption of preheating at an ambient temperature of −25 °C exceeds 80 % of the rated capacity of the experimental battery pack.