Nanoscale Projection Hard X-Ray Microscope for Statistical Analysis of Chemical Heterogeneity in Lithium-Ion Battery Cathodes

Spatiotemporal heterogeneity of the state of charge (SOC) in battery electrodes significantly impairs the rate capability and cycle life of Li-ion batteries (LIBs). However, mapping of this heterogeneity is challenging due to the absence of experimental methods that can quantify SOC across the entire electrode scale, while also offering the nanoscale resolution for in-depth analysis of individual particles. Here, we report an advanced projection hard X-ray microscopy (PXM) offering a nanometric resolution with a large field-of-view, and high chemical sensitivity, significantly minimizing beam damage by lowering beam flux 10⁻⁴ times compared to traditional transmission X-ray microscopy (TXM) while sufficiently maintaining fast X-ray absorption near edge structure (XANES) imaging speed. Employing full-field imaging on hundreds of Ni-rich layered oxide particles during real-time (de)lithiation at various C-rates, we probed the origin of SOC heterogeneities, and revealed that the battery degradation does not occur uniformly across the entire electrode but progresses differently at the level of individual particles.