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

The aprotic Li-O 2 battery (LOB) has the highest theoretical energy density of any rechargeable batteries. However, such system has been largely restricted by the electrochemically formed lithium peroxide (Li 2 O 2 ) 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 thickness less than 50 nm, a non-crystalline Li 2 O 2 film with thickness of more than 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 coupling also forms a direct charge transfer channel from Ce-4f of CeO 2 to O 2 2 - ${\rm{O}}_2^{2 - }$ -π* of Li 2 O 2 , eventually leading to submicron-thick Li 2 O 2 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. This article is protected by copyright. All rights reserved.