▎ 摘　　要

MnO2-graphene nanosheet (GNS) composite air electrode made by mixing aqueous GNS colloids and aqueous MnO2 dispersions was prepared for Li-air batteries. The composite air electrode delivered ultrahigh discharge capacity and presented bifunctional catalytic effects for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, Over 30 cycles was achieved with a capacity utilization of 1500 mAh/g by using MnO2-GNS composite air electrode, indicating its great potential for applications in the field of rechargeable Li-air batteries. (C) 2012 The Electrochemical Society. [DO!: 10.1149/2.043212jes] All rights reserved.