Abstract
Optimal fast charging is an important factor in battery management systems (BMS). Traditional charging strategies for lithium-ion batteries, such as the constant current–constant voltage (CC–CV) pattern, do not take capacity aging mechanisms into account, which are not only disadvantageous in the life-time usage of the batteries, but also unsafe. In this paper, we employ the dynamic optimization (DP) method to achieve the optimal charging current curve for a lithium-ion battery by introducing limits on the intercalation-induced stresses and the solid–liquid interface film growth based on an electrochemical–thermal model. Furthermore, the backstepping technique is utilized to control the temperature to avoid overheating. This paper concentrates on solving the issue of minimizing charging time in a given target State of Charge (SoC), while limiting the capacity loss caused by intercalation-induced stresses and film formation. The results indicate that the proposed optimal charging method in this paper offers a good compromise between the charging time and battery aging.
Highlights
Lithium-ion batteries have been used in many electronic products due to their high cell voltage, high energy density, high power density, convenient operating temperature range, lack of memory property, and high cycle life [1]
On the basis of the open circuit voltage (OCV)-resistance equivalent circuit model, Abdollahi et al [3] presented a closed-form solution for optimally charging a lithium-ion battery; the target function is established through a combination of two consumption functions: time-to-charge (TTC) and energy losses (EL)
Controller is employed to implement this close-loop method and the results indicate that the proposed approach achieved a 20% faster charging rate with an identical total temperature increase as compared to the constant current–constant voltage (CC–CV) technique
Summary
Lithium-ion batteries have been used in many electronic products due to their high cell voltage, high energy density, high power density, convenient operating temperature range, lack of memory property, and high cycle life [1]. Considering the influence of intercalation-induced stress on aging, Suthar et al [14] used dynamic optimization to achieve the optimal current profile to fast charge a lithium-ion battery through a single-particle model while coupling this with the intercalation-induced stress generation model. This was the first time protocols for optimally charging batteries while ensuring a minimal mechanical cost to the electrode particles during intercalation were demonstrated. On the basis of maintaining a constant temperature using the backstepping control method and minimizing the charging time while limiting intercalation-induced stress and the film growth to an appropriate range are the main contributions of this paper. Electrochemical–Thermal Model with Intercalation-Induced Stress and Film Growth
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