Abstract
Fluorinated graphene (FG) has been a star material as a new derivative of graphene. In this paper, a series of fluorinated graphene materials are prepared by using N, O-doped graphene aerogel as precursor via a direct fluorination method, and the effect of fluorination temperature on the FG structure is investigated. The prepared FG samples are systematically characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. It is found that the structure of FG, including features such as layer size, chemical composition, chemical bond state of the component elements, etc., is significantly related to the fluorination temperature. With the change of the fluorination temperature, fluorine atoms enter the graphene framework by a substitution process of the N, O-containing groups, including residual phenol, ether, carbonyl groups, or C–N groups, and the addition to CC bonds, subsequently forming a fluoride with different fluorine contents. The fluorine content increases as the fluorination temperature increases from 200 °C to 300 °C, but decreases at a fluorination temperature of 350 °C due to the decomposition of the fluorinated graphene. The prepared FG samples are used as cathode material for lithium primary batteries. The FG sample prepared at 300 °C gives a high specific capacity of 632 mAh g−1 and a discharge plateau of 2.35 V at a current density of 10 mA g−1, corresponding to a high energy density of 1485 Wh kg−1.
Highlights
Graphene, the world’s first two-dimensional (2D) material, was first isolated and characterized in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester
F2 is dangerous, the direct fluorination method by F2 still has many advantages compared to the liquid exfoliation methods and other fluorine resources (e.g., XeF2 ): this process can be scaled up, F2 has been large-scale produced by electrolysis technology, the F/C ratio can be finely controlled by varying the F2 concentration and fluorination temperature, and high F/C ratio can be obtained, which is very important for the cathode material of lithium primary batteries
The Fluorinated graphene (FG)-250 prepared at 250 ◦ C showed a high discharge plateau about 3.0 V and a moderate discharge capacity of 512 mAh g−1 at a current density of 10 mA g−1, while the FG-300 prepared at 300 gives 632 mAh g−1 and 2.35 V
Summary
The world’s first two-dimensional (2D) material, was first isolated and characterized in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. F2 is dangerous, the direct fluorination method by F2 still has many advantages compared to the liquid exfoliation methods and other fluorine resources (e.g., XeF2 ): this process can be scaled up, F2 has been large-scale produced by electrolysis technology, the F/C ratio can be finely controlled by varying the F2 concentration and fluorination temperature, and high F/C ratio can be obtained, which is very important for the cathode material of lithium primary batteries. Hydrogels and aerogels prepared through reduction induced self-assembly of graphene oxides have attracted significant attention These materials possess a three-dimensional (3D) porous structure, large specific surface area, and abundant heteroatom doping. The FG-250 prepared at 250 ◦ C showed a high discharge plateau about 3.0 V and a moderate discharge capacity of 512 mAh g−1 at a current density of 10 mA g−1 , while the FG-300 prepared at 300 gives 632 mAh g−1 and 2.35 V
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