A Self-Adaptive Multistage Constant Current Fast-Charging Strategy for Lithium-Ion Batteries Integrating Cooling Strategy

This study proposes a self-adaptive multistage constant current (SAMCC) fast-charging strategy for a battery at high ambient temperatures (40 °C). This strategy contains an electrothermal-degradation model for the battery and integrates a balanced cooling strategy. To realize the self-adaption of the algorithm, the genetic algorithm is used to determine the stage number of the charging strategy and the current in each stage. To balance the charging time and the capacity loss, the Pareto curve is adopted. Then, the SAMCC strategy is used for a 50-Ah prismatic battery. According to the results, the constraint condition of <inline-formula> <tex-math notation="LaTeX">$U_{\mathrm {b}} \le4.2$ </tex-math></inline-formula> V and the small currents in the second, third, and fourth stages make the SAMCC avoid over-charging, and the active cooling strategy eliminates overheating in the battery. At high ambient temperatures, the terminal voltage of the battery charged by the SAMCC never goes over 4.2 V, and its maximum temperature is 43 °C. Moreover, the SAMCC is compared with the standard fast-charging strategy (SFC) to prove its superiority. Its charging time tested at 40 °C is 644 s shorter than that of the SFC, and its state of health (SOH) is only 0.12% lower than that of the SFC at the cycle number of 100.