Investigation the usuability of heteroatom doped graphene as a cathode in Lİ-air batteri̇es

The increasing trend for energy and mobility caused environmental problems, which increase day by day, have revealed the need for efficient use of energy and resulted the need for rechargeable batteries to increase rapidly. Li-air batteries are the most probable alternative to internal combustion engines with their theoretical specific capacity. For this reason, efforts to produce rechargeable Li-air batteries have gained momentum in recent years. In this study, nitrogen-doped graphene (N-GN), silicon-nitrogen-doped graphene (Si-N-GN) and iron-nitrogen-doped graphene (Fe-N-GN) were synthesized by solvothermal method and their behavior as cathode electrocatalyst in Li-ion batteries have been determined. The morphological structures of the samples have been characterized by energy dispersive scanning electron microscopy (SEM-EDS) and N2 adsorption method, crystal structures by X-ray diffraction (XRD) and Raman spectrometry, elemental composition and binding configurations of elements by X-ray photoelectron spectrometry (XPS). Accordingly, N-GN consists of regular micro- and meso-pores in which dense layers of graphene are connected to each other, Si-N-GN has a structure consisting of multiple graphene plates in dispersed form, and Fe-N-GN is composed of graphene plates. Besides, it has been observed that it has micro-sized FexOy structures covered with graphene having Fe-C and Fe-N bonding patterns. The electrocatalytic behaviors of the synthesized samples were determined in solutions containing 1.0 M lithiumtetrafluorosulfonimide (LiTFSI) or 1.0 M lithiumhexafluorophosphate (LiTFSI), prepared with acetonitrile (AN), dimethylsulfoxide (DMSO), propylene carbonate (PC) or tetraethylene glycolmethylether (TEGDME) solvents. Accordingly, it was observed that in general, DMSO is oxidized electrocatalytically by all graphene samples and the samples have weak electrocatalytic activity in TEGDME electrolytes. A discharge capacity of 1480 mAh / g was obtained in the PC solution containing 1.0 M LiTFSI for Si-N-GN.