Fast self-preheating system and energy conversion model for lithium-ion batteries under low-temperature conditions

Low temperature is one of the major drawbacks of electric cars in high latitudes. This problem can be addressed using a battery self-preheating system. The existing self-heating systems have problems, such as slow heating rate, complex control system, single thermal management function and poor safety. Herein, we propose a conductive phase change material (cPCM)-based self-preheating system that generates heat simultaneously using the internal resistance of cells and external resistance of the cPCM. This self-preheating system shows a high heating rate of 17.14 degrees C/min and excellent temperature uniformity (temperature difference of 3.58 degrees C). The system can preheat the battery safely in the capacity range of 20%-100%. When the battery pack is set in-20 degrees C, the effective electric energy can be increased by 550% after preheating. An energy conversion model is also built to measure the relationship between the energy improvement of battery and the energy consumption by pre-heating. This energy conversion model can help the system to make the optimal preheating strategy and obtain the maximum discharge energy. Nevertheless, based on the outcome of this study, this self-preheating strategy can effectively solve the problem of battery in low temperatures and maximize the effective electric energy of the battery.

Automated summary

Low temperature is a major issue for electric cars in high latitudes. A conductive phase change material (cPCM)-based self-preheating system is proposed to address this problem. The system utilizes the internal resistance of cells and the external resistance of the cPCM to generate heat simultaneously, achieving a high heating rate and temperature uniformity. The system can safely preheat the battery and significantly increase the effective electric energy. An energy conversion model is developed to optimize the preheating strategy and maximize the discharge energy.