▎ 摘　　要

In this study, free-standing porous graphene papers for high-capacity and reversible Li-O-2 battery cathodes are investigated. The graphene paper-like films were fabricated by the assembling of graphene nanoplatelets (GNPs) with the aid of graphene oxides (GOs) as a stabilizer, using a vacuum-assisted filtration method. By using GOs as a stabilizer, the GNP/GO films were fabricated with a paper-like form and they exhibited a highly wrinkled and disordered morphology. Moreover, the use of GNPs as a basic material eliminated the need for a post-annealing to recover the intrinsic electrical conductivity of graphene sheets. Subsequently, the GNP/GO paper could be directly used as a Li-O-2 battery cathode without any conducting additives and binders. The GNP/GO paper electrode showed a much higher discharge capacity in comparison to the reduced-GO paper and commercially available carbon papers. We also found that toroidal Li2O2 mainly nucleated and grew on discharge, and decomposed on charge with a relatively high O-2 evolution/consumption efficiency of 87%. However, a large number of Li2O2 particles grew inside the GNP/GO paper electrode, resulting in severe volume expansion of the electrode. This volume expansion could be the primary reason for the capacity fading on cycling. (C) 2015 Elsevier Ltd. All rights reserved.