The physics and chemistry of carbonaceous materials can be drastically modified through reaction with fluorine and fluorinated reagents. This behavior is due to the extreme reactivity of these gases that allow important changes in the electronic configuration of carbon, even at low temperatures. In many carbon-fluorine systems, the modification of either surface or bulk properties depends on the structural characteristics of the pristine material and/or the experimental parameters of the fluorination. The different types of C-F bonding present in the final compounds can be correlated using several physical investigations, including XPS and electron microscopies. Several reaction mechanisms have been proposed depending on the nature and morphology of the pristine carbon material. The influence of nanosized morphology will be demonstrated, as in carbon nanotubes, nanoparticles or nanographenes. The importance of such systems in electrochemistry and in energy storage devices (Li-ion batteries) will be pointed out, including the reactivity of carbon materials during the electrochemical synthesis of fluorine (F2) in molten KH.2HF, the production of graphene via the electrochemical decomposition of molten carbonates, yielding new kinds of fluorinated nano-carbons components for Li-ion batteries. The physical properties that can be drastically modified may concern: -Electrical conductivity in graphitised carbons and high-temperature treated carbon fibres, that may vary from insulating to metallic behavior, depending on the amount of intercalated fluorine; -Electrical permittivity in fluorinated carbon blacks; - Surface hydrophobic/hydrophilic balance in materials treated with fluorinated rf plasmas; -Reversible capacities of lithium-ion secondary batteries using F-treated carbon anodes; -New kinds of fluorinated nano-carbons allowing to provide higher potential and energy density values, thus improving the electrochemical performances of primary Li-battery.

When fluorine meets carbon: Reactivity mechanisms, structural changes and applications

255th National Meeting (2018)

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