▎ 摘　　要

Carbon is essential for the oxygen electrode in non-aqueous lithium-oxygen (Li-O-2) batteries for improving the electron conductivity of the electrode. However, it also leads to some side reactions when exposed to the Li2O2 product and the electrolyte, limiting the round-trip efficiency and coulombic efficiency of the batteries. In this paper, a carbon-embedded alpha-MnO2@graphene nanosheet (alpha-MnO2@GN) composite is introduced as a highly effective catalyst for Li-O-2 batteries. X-ray photoelectron spectroscopy (XPS) analysis showed that the Li2CO3 by-product was significantly reduced due to the isolation of carbon with the electrolyte and Li2O2. Thus, the composite could deliver a reversible capacity of similar to 2413 mAh g(-1) based on the total mass of the composite with an extremely high discharge voltage of similar to 2.92 V (only 40 mV lower than the thermodynamic potential) and a low charge voltage of similar to 3.72 V at a current density of 50 mA g(-1). The round-trip efficiency is calculated to be similar to 78% with a coulombic efficiency of almost 100%.