Experimental and Numerical Study of Pulse Charging Strategies on Lithium-Ion Battery Performance at Both Low and Room Temperatures

Abstract

Lithium-ion batteries are widely used in power electronic devices, electric vehicles, and large energy storage devices, which demand faster, safer and more durable charging methods. Compared with the conventional constant current and constant voltage charging method, pulse charging can both improve battery performance and shorten charging time. This dissertation investigates how pulse charging can shorten charging time under different temperature conditions and mitigate capacity loss over multiple cycles. This study combines experimental testing and numerical simulation. Firstly, this study designed experiments to evaluate pulse charging at different temperatures. Using the Taguchi method, we treated protection capacity ratio and pulse discharge current rate as control parameters. At low temperature, pulse charging with a 25 protection capacity ratio and a 12C pulse discharge rate reduced total charging time by approximately 11 compared to the conventional constant current and constant voltage charging strategy. At room temperature, three fundamental pulse modes (C-C, C-R and C-D) and several derived strategies were studied. Their effects on internal resistance and battery cycle life were then measured. The experimental results show that, under the same average input current, pulse charging yields an average internal resistance reduction of 15 compared to the constant current and constant voltage charging strategy, and shows a slower capacity decay rate over 800 charge and discharge cycles. These findings are also confirmed across lithium-ion batteries with various chemistries. Secondly, an electrochemical and thermal coupled model was developed in COMSOL Multiphysics to reveal the mechanisms of pulse charging. After validation, the model was used to study lithium-ion concentration and electrode lithium distributions inside the battery under different pulse charging protocols. The model results show that pulse charging, particularly the C-D mode, promotes a more uniform lithium-ion distribution within the battery, thereby improving charging performance of lithium-ion battery by reducing cell resistance. These findings are consistent with the experimental results. Finally, a multi-objective optimization method was used to find the optimal parameters for pulse charging at room temperature. The objectives were to minimize total charging time, minimize temperature rise and maximize charging efficiency. The resulting optimal pulse charging strategy can reduce charging time by 6.8 per cycle and lower temperature rise by more than 8 compared to conventional constant current and constant voltage charging. This research studied pulse charging of lithium-ion batteries at different temperatures through experimental design, numerical simulation, and optimization. Pulse charging improves the performance of lithium-ion batteries by saving charging time and reducing capacity loss. Numerical simulation provides deeper insight into lithium migration and diffusion dynamics under pulse conditions. This research lays a solid foundation for future charging protocol development.