Mitigating Reaction Barriers in Ni‐Rich Cathodes via Surface‐Bulk Coupling Strategy for Fast‐Charging

ABSTRACT Material degradation in layered oxide cathodes, particularly mechanical degradation, presents a “chicken or egg” dilemma as it may originate from either the surface or the bulk. Surface‐only or bulk‐only modifications have proven insufficient to resolve these intrinsic issues. While combined surface‐bulk strategies can mitigate degradation, they often require complex processes that increase costs and limit scalability. Here, we report a design that couples bulk structural stabilization with the in situ formation of a fast conductive interphase on Ni‐rich layered oxides. This dual approach yields a robust bulk framework and a stable surface with accelerated reaction kinetics, enabling a high‐rate capability of over 160 mAh g −1 at the current of 5 C and stable cycling over 200 cycles. Beyond performance gains, our results reveal atomic‐scale insights into the interplay between structural evolution, ionic transport, and electrochemical stability, offering a practical pathway to durable high‐nickel cathodes for fast‐charging batteries.