Suppressing High‐Current‐Induced Phase Separation in Ni‐Rich Layered Oxides by Electrochemically Manipulating Dynamic Lithium Distribution

Abstract Understanding the cycling rate‐dependent kinetics is crucial for managing the performance of batteries in high‐power applications. Although high cycling rates may induce reaction heterogeneity and affect battery lifetime and capacity utilization, such phase transformation dynamics are poorly understood and uncontrollable. In this study, synchrotron‐based operando X‐ray diffraction is performed to monitor the high‐current‐induced phase transformation kinetics of LiNi0.6Co0.2Mn0.2O2. The sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by exploiting the dependence of Li diffusivity on the Li content and electrochemically tuning the initial Li content and distribution, phase separation pathway can…