Heterogeneous Lithium Transport within Individual Single-Crystalline NCM Battery Particles

Probing the lithiation kinetics in solid-state electrodes is foundational for advancing high-efficacy battery technologies. Typically, a consistent and monotonic lithium gradient is anticipated across solid-solution single-crystalline battery constituents throughout the cycling process. Our exploration, centered on the heterogeneous lithium distribution within single-crystalline LiNi0.333Mn0.333Co0.333O2 nanostructures, utilized operando scanning transmission X-ray microscopy for precision. Contrary to the prevailing Fickian diffusion paradigm, our insights highlight the emergence of regions both rich and deficient in lithium, which exhibit dynamic behavior across battery cycles. This intricate interplay of intra-particle strain fields, capable of either concentrating or dispersing lithium, was authenticated using Bragg coherent X-ray diffraction methodologies. Significantly, we elucidated that regions with sparse lithium proximal to the particle surface can modulate the overarching charge transfer resistance and offer avenues for in-situ optimization. This investigation provides a renewed perspective on the intricacies of nanoscale solid-state guest diffusion, heralding implications for battery rate performance and durability.