Graphene-like δ-MnO2 decorated with ultrafine CeO2 as a highly efficient catalyst for long-life lithium–oxygen batteries

Abstract

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.