Innovative Fast-Charging Protocol Incorporating Proactive Lithium-Plating Suppression Pulses for Lithium-Ion Batteries: Protocol Design, Validation, and Post-Mortem Analysis

Abstract

Conventional fast-charging using a high constant current can ultimately accelerate uncontrolled Li plating on the graphite anode, resulting in degradation and poor cycle life of Li-ion batteries (LIBs). Therefore, identifying suitable fast-charging methods for LIBs is beneficial for the widespread use of electric vehicles (EVs). Herein, an innovative fast-charging protocol, designed by combining an active control pulse (ACP) with a multi-step fast-charging method (M-ACP), is proposed to mitigate issues related to Li plating and byproduct formation on the graphite anode during fast-charging. Because M-ACP not only reduces charging time but also actively prevents Li plating on the graphite anode surface, the 60 Ah pouch cell used in EVs that employ the M-ACP protocol exhibits an extended lifetime with no capacity fading over 2000 cycles. The degradation behavior of the negative electrodes, which is strongly correlated to the improved performance of M-ACP cells, is demonstrated using non-destructive diagnostic techniques and post-mortem analyses. The M-ACP cell exhibits significantly less active material and Li loss, and decreased solid electrolyte interphase layer growth on graphite, owing to effective mitigation of Li+ accumulation at the electrode/electrolyte interface. Consequently, the distinguished fast-charging protocol effectively decelerates the degradation of the negative electrode, leading to outstanding electrochemical performance. An innovative fast-charging protocol combining an active control pulse (ACP) with a multi-step fast-charging method (M-ACP) can effectively alleviate concentration polarization within the LIB, preventing Li metal plating and resultant cell degradation. Consequently, M-ACP restrains the serious degradation of the negative electrode in LIBs, leading to outstanding electrochemical performance. image