Persistent and partially mobile oxygen vacancies in Li-rich layered oxides

Increasing the energy density of layered oxide battery electrodes is challenging as accessing high states delithiation often triggers voltage degradation and oxygen release. Here we utilize transmission-based X-ray absorption spectromicroscopy ptychography on mechanically cross-sectioned Li1.18–xNi0.21Mn0.53Co0.08O2–? to quantitatively profile deficiency over cycling at nanoscale. The penetrates into bulk individual primary particles (~200 nm) well-described by vacancy diffusion. Using an array characterization techniques, demonstrate that, surprisingly, vacancies that persist within native phase are indeed responsible for observed spectroscopic changes. We additionally show arrangement secondary (~5 ?m) causes considerable heterogeneity in extent release between particles. Our work merges ensemble length-spanning methods informs promising approaches mitigate deleterious effects lithium-ion electrodes. Oxygen Li-rich oxides both fundamental practical interest batteries, but a varied mechanistic understanding exists. authors evaluate extended cycles present comprehensive picture phenomenon unifies current explanations.