Premodified Oxygen Vacancies in Carbon-Coated NCM Cathodes for Enhanced High-Rate Cycling Stability

Metal oxide-based cathode (NCM) materials are key components of secondary batteries, the sufficient stability of which is vital for ensuring high-rate capability and safety. Nevertheless, the unavoidable oxygen vacancies of NCM during the cycling processes can cause capacity degradation, gas evolution, and thermal runaway. Here, we develop a carbon-coating strategy to premodify oxygen vacancies in LiNi1/3Co1/3Mn1/3O2 (NCM111) by an albumen-templated spray drying method. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicate that the oxygen vacancy ratios can be adjusted without harming the hexagonal layer structure of the NCM. The optimized NCM111 cathode presents enhanced reversible capacity (198.9 mAh g–1 at 0.5 C) and superior capacity retention after 200 cycles (89.9% at 5 C). Mechanistic studies show that moderate premodified oxygen vacancies in NCM can facilitate the preferential crystal orientation of {010} facets for rapid Li+ diffusion, contraction of the transition metal slab, expansion of the Li slab, and inhibition of cation mixing. The findings of this work offer a thorough understanding of oxygen vacancies and the relevant changes in the crystal and electronic structures of NCM.