Unraveling the Impacts of Asymmetric Cycling Protocol in Lithium‐Ion Batteries: The Correlative Relationship Between Electrochemical Stability and Charging–Discharging Rates

ABSTRACT The widespread adoption of electric vehicles (EVs) is constrained by long charging times and associated range anxiety, necessitating the development of fast‐charging, high‐energy‐density lithium‐ion batteries. While high‐capacity nickel‐rich cathodes like LiNi 0 . 9 Mn 0 . 05 Co 0 . 05 O 2 (NMC) are promising, their poor rate capability under high charging currents accelerates structural degradation, impacting both cycle life and power output. This study systematically investigates the effects of asymmetric charge–discharge protocols on the electrochemical and structural stability of NMC/graphite batteries. By comparing three cycling regimes—slow charge‐fast discharge (0.5C/2D), symmetric constant‐current (1C/1D), and fast charge‐slow discharge (2C/0.5D)—we reveal that the 0.5C/2D protocol significantly enhances battery longevity by reducing phase inhomogeneity, mitigating structural stress, and promoting uniform lithium‐ion distribution. Conversely, the 2C/0.5D protocol triggers severe phase transitions, electrode microcracking, and rapid capacity fade. Multi‐scale characterizations (in situ XRD, Raman, ToF‐SIMS, and EIS) confirm that high‐rate charging induces non‐uniform lithium diffusion and exacerbates transition metal dissolution, which destabilizes the anode's solid electrolyte interphase (SEI). Simulations validate that slow charging minimizes stress gradients and preserves interfacial stability. Furthermore, an application‐oriented dynamic charging strategy was designed and validated, effectively balancing fast‐charging efficiency with long‐term structural durability. These findings provide critical guidance for advancing charging algorithms in high‐power EV applications.