▎ 摘　　要

In this study, we employed an efficient and straightforward synthesis method for the functionalization and stitching of graphene oxide (GO) sheets with ethylenediamine (EDA). 3-D-structured GO-EDA was prepared by low reduction of the oxygen-containing functional groups of GO. The EDA was used as a nitrogen source to create the nitrogen-doped graphene (N-graphene), as well as a factor to control the self-assembly of graphene nanosheets into 3-D structures. The morphology, composition, and covalently grafted functional groups of GO-EDA were investigated by FT-IR and Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and various electrochemical techniques. GO-EDA exhibits a layered structure resembling graphite, with an enhanced d-spacing of 0.373 nm compared with graphite (0.348 nm). The results showed that the porous channels of the synthesized GO-EDA facilitate the efficient transportation of lithium ions through the electrolyte-filled channels. The first discharge and charge showed specific capacities of 830.34 mAh g(-1) and 664 mAh g(-1), respectively at the current density of 100 mA g(-1), corresponding to an initial coulombic efficiency of ca. similar to 80%; superior to the GO reference (27.8%). Moreover, GO-EDA displayed improve cycling stability (maintaining a reversible capacity of similar to 300 mAh g(-1) at 200 mA g(-1) after 100 cycles). The improved electrochemical operation was ascribed to enhanced ion (Li+) transport within the graphitic layers by the increased d-spacing due to the inserted functional groups. (C) 2019 Published by Elsevier B.V.