Graphene-like δ-MnO2 decorated with ultrafine CeO2 as a highly efficient catalyst for long-life lithium–oxygen batteries
Lithium–oxygen (Li–O2) cells are receiving intense interest because of their extremely high energy density. A highly efficient catalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key factor influencing the performance of lithium–oxygen cells. In this work, we prepared a highly efficient CeO2-decorated δ-MnO2 (CeO2/δ-MnO2) catalyst which is composed of graphene-like δ-MnO2 with ultrafine CeO2 nanocrystals decorated on it. Li–O2 cells with the CeO2/δ-MnO2 catalyst exhibit superior electrochemical performance, including high discharge specific capacity (8260 mA h g−1 at 100 mA g−1), good rate capability (735 mA h g−1 at 1600 mA g−1), and excellent cycling stability (296 cycles at a limited capacity of 500 mA h g−1), which is much better than that with a bare δ-MnO2 catalyst. The achievement of excellent electrochemical performance is attributed to the highly efficient co-catalytic ability of δ-MnO2 and CeO2 and the desirable graphene-like architecture of the CeO2/δ-MnO2 catalyst, as well as the formation of the thin-layered discharge product Li2O2.