Highly reversible oxygen redox in layered compounds enabled by surface polyanions.

ABSTRACT: Oxygen-anion redox in lithium-rich layered oxides can boost the capacity of lithium-ion battery cathodes. However, the over-oxidation of oxygen at highly charged states aggravates irreversible structure changes and deteriorates cycle performance. Here, we investigate the mechanism of surface degradation caused by oxygen oxidation and the kinetics of surface reconstruction. Considering Li₂MnO₃, we show through density functional theory calculations that a high energy orbital (lO_2p') at under-coordinated surface oxygen prefers over-oxidation over bulk oxygen, and that surface oxygen release is then kinetically favored during charging. We use a simple strategy of turning under-coordinated surface oxygen into polyanionic (SO₄)^2-, and show

SUBMITTER: Chen Q 

PROVIDER: S-EPMC7343805 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature