A rapid self-heating strategy of lithium-ion battery at low temperatures based on bidirectional pulse current without external power

Polarization is a major problem for lithium-ion batteries (LIBs) at low temperatures. To realize rapid preheating of LIBs at low temperatures, a self-heating strategy based on bidirectional pulse current without external power is proposed. Four inductances and one direct current/direct current (DC/DC) converter are applied to the system. An electrothermal coupling model of LIBs and a performance evaluation model of the system are established to investigate the effects of circuit parameters and initial state-of-charge (SOC) on the heating performance, including the heating time, SOC utilization ratio (SUR), and heating efficiency. The results show that the LIBs can be warmed up from −10 °C to 0 °C in approximately 120 s. It is concluded that reducing the discharge inductance can increase the heating rate, SUR, and heating efficiency. However, the excessive reduction of the discharge inductance would cause a significant voltage drop, which will reduce the voltage to below the cut-off voltage. In addition, a comparative study shows that when the initial SOC values of the two battery packs are different, the heating time will be reduced. A higher initial SOC for one battery pack can increase the heating speed and SUR at the expense of the heating efficiency. • A bidirectional pulse current heating strategy without external power was proposed. • Effects of circuit parameters and initial SOC on heating performance were analyzed. • LIBs can be heated from −10 °C to 0 °C in 120 s with little capacity degradation. • Unbalanced initial SOCs of the battery packs can improve the heating rate and SUR.