• Energy Research

Understanding ion adsorption in nanoporous carbon electrodes is of great importance for designing the next-generation of high energy density electrical double-layer capacitors. In this work, X-ray scattering is used for investigating the impregnation of nanoporous carbons with electrolytes in the absence of applied potential. We are able to show that interactions between the carbon surface and electrolytes allow adsorption to take place in sub-nanopores, thus confirming experimentally for the first time the results predicted by molecular dynamic simulations.

Abstract By varying excitation energy from ultraviolet to infrared, Raman spectra obtained from both cokes and pyrocarbons revealed the evolution of each band. While the spectra of different samples can be very similar at given wavelength, the wavelength dependence should be considered for correlating spectral features to crystallite size L a . The D′ band was found to vanish in the UV range. The D band was fitted with one or two Lorentzians for crystallite sizes larger than ∼5 nm or below respectively, both centered on the same wavenumber. Both the D band intensity and integrated intensity were accurately obtained, and used to question the range of use of the Tuinstra–Koenig law. The G band shape is well fitted and its width increases monotonously with 2 L a I D / I G was found to vary with the excitation energy E L as E L - b with 1 b L a and the sample type. We question the validity of the empirical laws from the literature for having been obtained on a limited sampling and wrongly considered to remain valid over the full ranges of both L a and wavelengths. Considering the G band width instead is emphasized.