▎ 摘　　要

In this study, in situ differential electrochemical mass spectrometry was employed to investigate the electrochemical rechargeability of two types of graphene nanoplatelets (GNPs) as electrode materials for lithium-oxygen batteries by evaluating oxygen efficiency as well as coulombic efficiency. GNPs having hydrophobic surfaces exhibit much higher specific capacity than those having hydrophilic surfaces. When lithium nitrate-N,N-dimethylacetamide (LiNO3-DMAc) is used as the electrolyte, the lithium-oxygen battery exhibits a long cycle life, and unwanted side reactions are effectively suppressed. The LiNO3-DMAc electrolyte is more stable than the lithium bis(trifluoromethane)sulfonamide-tetraethylene glycol dimethyl ether electrolyte, as evidenced by high O-2 evolution and low CO2 evolution. (C) 2015 Elsevier B.V. All rights reserved.