Unlock Restricted Capacity via OCe Hybridization for LiOxygen Batteries

Abstract

AbstractThe aprotic Li‐O2 battery (LOB) has the highest theoretical energy density of any rechargeable batteries. However, such system is largely restricted by the electrochemically formed lithium peroxide (Li2O2) on the cathode surface, leading ultimately to low actual capacities and early cell death. In contrast to the surface‐mediated growth of thin film with a thickness <50 nm, a non‐crystalline Li2O2 film with a thickness of >400 nm can be formed via an optimal OCe hybridized electronic structure. Specially, oxygen can react with dissolved cerium cations in the electrolyte via a cerium‐oxygen reaction to form a high‐energy faceted cerium oxide catalyst, which not only generates a great number of non‐saturable active sites, but also erects electron transport bridges between the lattice O and adjacent Ce atoms. Such CeO orbital hybridization also forms a direct charge transfer channel from Ce‐4f of CeO2 to ‐π* of Li2O2, eventually leading to submicron‐thick Li2O2 shells via a subsequent lithium‐oxygen reaction. Relying on the above merits, this work unlocks the rechargeable capacities of LOB from restricted 1000 to unprecedented 10 000 mAh g−1 with good cyclabilities and reduced charge–discharge overpotentials.