Oxygen Vacancies Design of Anionic Site to Optimize Electrode–Electrolyte Interface Properties on a Li-Rich Cathode

Lithium-rich cathode materials (LROs) elicit great interest due to their excellent electrochemical performance and high energy density (>900 Wh kg-1). Anionic redox (AR) contributes additional capacity to LROs but causes unfavorable structural degradation and oxygen release. Surface oxygen vacancies (Vos) in LROs directly affect anion redox, and the effects of their concentration variations have been reported both positively and negatively in the current studies. Therefore, controlling the concentration of Vos is essential to balancing these advantages and disadvantages. In this work, the initial discharge capacity of LROs with an appropriate Vos concentration is increased to 305.1 mAh g-1, with an energy density as high as 1060.0 Wh kg-1. In addition, in situ XRD, soft X-ray absorption spectroscopy (sXAS), and differential electrochemical mass spectrometry (DEMS) were employed to determine and further elucidate the mechanism by which their concentration affects performance.