A SOC-Based Fast Charging Optimization Strategy with Coupled Electro-Thermal-Aging Model for Lithium-ion Batteries

Enabling fast charging of lithium-ion batteries (LIBs) may accelerate the commercial application of electric vehicles (EVs). This paper proposes a SOC-based fast charging optimization strategy with the coupled electro-thermal-aging model. The state of charge (SOC), instead of charge cut-off voltage Ut, max, is employed to govern the multi-stage constant current (MSCC) charging process. The optimal charging current sequence of MSCC is determined by the dynamic programming (DP). And the Pareto curve is used to evaluate the performance of the proposed strategy. Considering the tradeoff between optimization effect and computational complexity, the optimal number of charging stages is selected as 4. The Pareto curve illustrates that the proposed SOC-based fast charging strategy dominates the equivalent CCCV charging method in shortening the charging time, reducing the energy loss and capacity loss. Moreover, the impacts of maximum charging voltage and aging on the optimization results are analysed in detail.