A fast-response preheating system coupled with supercapacitor and electric conductive phase change materials for lithium-ion battery energy storage system at low temperatures

The electrochemical performance of lithium batteries deteriorates seriously at low temperatures, resulting in a slower response speed of the energy storage system (ESS). In the ESS, supercapacitor (SC) can operate at −40 °C and reserve time for battery preheating. However, the current battery preheating strategy has a slow heating rate and cannot preheat batteries to a comfortable temperature range during the time reserved by SC. This study proposes a preheating system that combines the instantaneous high-power discharge of SC with the efficient electro-to-thermal conversion of ECPCM, which has a super-fast preheating rate and contributes to the fast response of ESS at low temperatures. Under extreme conditions of −40 °C, the preheating system can recover >85 % discharge capacity and voltage of the battery system in 2 min. By adjusting SC capacitance and ECPCM resistance, the preheating rate of the battery system can reach 69.5 °C/min, and the temperature difference is less than 5 °C. Moreover, the pulse current of SC can reduce the temperature difference inside the battery within 5 °C. The preheating system can also enable the battery system quickly enter super-charging mode, greatly reducing the charging time. The total charging time was reduced by 72 % when the battery pack was preheated to 20 °C. Nevertheless, based on the outcome of this study, this preheating strategy can effectively improve the low-temperature response speed of the ESS and meet the requirements of the microgrid. •A rapid preheating strategy for microgrid hybrid energy storage system is proposed.•The system can recover >85 % discharge capacity of the system in 2 min.•The preheating rate can reach 69.5 °C/min and temperature difference is below 5 °C.•The temperature difference inside the battery is reduced to 5 °C by pulse heating.•The preheating strategy reduces the charging time of the battery system by 72 %.