Comparative Analysis of Charging Protocol for Degradation Reduction and Remaining-Useful-Life Enhancement of a Lithium-Ion Battery

Abstract

Lithium-ion batteries are widely used in various mobile applications, particularly in electric vehicles, due to their high energy and power density. However, repeated charge and discharge cycles and inappropriate charging protocols can lead to its early degradation, resulting in reduced capacity and high internal resistance. Even though some research has proposed an optimal charging method of a lithium-ion battery, an effective method is yet to be identified for both time and degradation reduction. Herein, an effective charging protocol that minimizes battery life degradation thereby enhancing its remaining-useful-life is proposed. The proposed protocol is an adaptive multistage constant current (MCC) and pulse charging (PC) protocol, utilizing time-dependent current charging profiles to prevent battery degradation with state-of-charge (SOC) variation and pulse relaxation intervals. An extended Kalman filter algorithm for accuracy SOC estimation is embedded with the charging protocol. The proposed method is evaluated with other charging profiles, including constant current, MCC, and PC protocols, to evaluate its performance. The results show that among the four cases proposed, only the PC protocol outperforms other charging protocols, achieving a balance between fast charging and battery degradation prevention, making it better applicable for use in practical battery charge applications.