Dynamic structural evolution of oxygen vacancies in lithium rich layered composites cathodes for Li-ion batteries

ABSTRACT Understanding structural evolution in lithium-rich layered oxidized composites (LLO) is fundamental to design improved cathode materials for rechargeable lithium-ion batteries (LIBs). In particular, retrieving quantitative structural parameters are essential factors to unveil the hidden phases or atomic orderings affecting the properties of LIBs. The oxygen-vacancies heterogeneity is revealed in 0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2 (LR-NCM) during de-lithiation process via rigid structural refinements. Through the in-situ/ex-situ X-ray absorption spectroscopy (XAS) in synergy with first principles calculations, the dynamic structural (and electronic) evolution of oxygen vacancies is confirmed to be in the form of ⿴MnO2⿴ (⿴ represents vacancy site) for Li2MnO3 component. With the formation of oxygen vacancies in Li2MnO3 component, the oxygen-vacancy-bearing structure ⿴MnO2⿴ also play significant supporting role on its parent structure without obvious Mn ions activity. This result offers new perspectives on synergistic improvement in the electronic and structural evolution, which is the key to design high energy density cathode materials for next-generation lithium ion batteries.