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

Abstract

The 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 (Li2 O2 ) 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 <50nm, a non-crystalline Li2 O2 film with a thickness of >400nm 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 hybridizationalso forms a direct charge transfer channel from Ce-4f of CeO2 to -π* of Li2 O2 , eventually leading to submicron-thick Li2 O2 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 10000mAhg-1 with good cyclabilities and reduced charge-discharge overpotentials.