Research On Solvothermally Exfoliated Fluorographene And Its Electrochemical Properties

Owing to its distinctive mechanical, magnetic, electronic, and optical properties,Fluorographene (FG), as a derivative of graphene, have drawn the considerableattention. FG is regarded as one of important candidate materials for advancedtechnological applications in interface science, nanometer scale device, energy storageand other fields.In this paper, the solvothermal exfoliation of fluorinated graphite using twoorganic solvents (acetonitrile, chloroform) with low boiling points were employed toprepare FG nanosheets. This exfoliation exhibits a yield up to15%, which is almostthree-fold higher than that of FG nanosheets prepared only by ultrasonication. Fewlayered (<5) FG nanosheets exfoliated by acetonitrile and chloroform shows atransparent wrinkled structure and disordered regularity. Compared with the structureof layers in fluorinated graphite, the structure of fluorographene obtained bysolvothermal intercalation method has no significant change in structure. X-ray photoelectron spectroscopy spectra and Fourier transform infrared spectra indicated that theintercalation of chloroform led to partial transformation from covalent C-F bonds tosemi-ionic C-F bonds at150oC. Meanwhile, a decrease in degree of fluorine was alsoobserved in the FG which was prepared in chloroform at180oC.The electrochemical performance of FG nanosheets was tested as the cathodematerial of Li-battery at room temperature. Compared with the Li-battery usingF-graphite, the FG nanosheet cathode displayed an excellent electrochemicalperformance with an improved discharge voltage, specific capacities and ratecapability. Lithium primary battery using FG cathode exhibited a remarkabledischarge rate performance because of good Li+diffusion and charge mobility throughnanosheets. FG nanosheets exfoliated by chloroform at150℃showed a maximumpower density of4038W kg-1at3C because the intercalation of chloroform led to thepartial transformation from covalent C-F bonds to semi-ionic C-F bonds. Resultsindicate that solvothermal exfoliation by low-boiling-point solvents is a facile andhigh-yield approach to prepare high-purity FG nanosheets.