Abstract:An electric double-layer capacitor (EDLC) has high potential for storing electrical energy at a high power density. It was reported that a narrow nanopore system provides higher performance of EDLCs. In such a system, propylene carbonate (PC) is generally used as a solvent in EDLCs. Hence, the structure of PC in the slit-shaped carbon nanopores should be investigated to reveal the EDLC mechanism. In this paper, grand canonical Monte Carlo simulation of PC adsorbed in nanopores was performed to elucidate molecu… Show more
“…5 ), intensity for angles <7° decreases, indicating pore impregnation by EMI, BF4 whatever the pore size. These results provide experimental evidence of the hypothesis deduced from molecular dynamic modelling [ 24 ] and more precisely of CDC porous carbon/RTIL interface modelling [ 16 , 25 ] indicating the quasi instantaneous loading of sub-nanometer pores by charged species. Fig.…”
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.
“…5 ), intensity for angles <7° decreases, indicating pore impregnation by EMI, BF4 whatever the pore size. These results provide experimental evidence of the hypothesis deduced from molecular dynamic modelling [ 24 ] and more precisely of CDC porous carbon/RTIL interface modelling [ 16 , 25 ] indicating the quasi instantaneous loading of sub-nanometer pores by charged species. Fig.…”
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.
“…Also, the amplitude of the confined PC is larger than that of bulk PC. Ohba et al evaluated the PC intermolecular structure in the carbon slit pore with grand canonical Monte Carlo (GCMC) simulation using a 13-centered model for a rigid PC molecule . The simulation predicts both the shorter distance shift of the nearest-neighbor peak and enhancement of the amplitude for the confined PC molecules, as observed above.…”
International audienceWe report the vertical alignment of propylene carbonate (PC) molecules interacting with Et4N+ and BF4– which are confined in extremely narrow slit pores (w ∼ 0.7 nm) of carbide-derived carbon and pitch-based activated carbon fiber. On the basis of X-ray diffraction (XRD), electron radial distribution function analysis reveals that the nearest PC–PC distance is 0.05–0.06 nm shorter than that in the bulk solution, indicating dense packing of PC molecules in the pores. This confinement effect results from the vertically aligned PC molecules, which are indicated by the reverse Monte Carlo analysis. The ensemble structure of PC molecules in the subnanometer carbon pores will provide better understanding the supercapacitor function
“…ACF2 had a smaller percentage of Li ions in the micropores and a slightly larger average solvation number for the Li ions compared to C acid and C base , although their micropore size distribution of ∼0.54–1.0 nm was nearly the same. Strong interactions with the wide carbon wall of the micropores in ACF2 likely restricted the access of PC-solvating Li ions to the micropores . The micropores of C acid and C base , constructed with short lateral size, were more accessible to the PC-solvating Li ions, promoting desolvation of the PC molecules in micropores with a size similar to the Stokes’ diameter of Li + in PC.…”
Section: Resultsmentioning
confidence: 99%
“…Strong interactions with the wide carbon wall of the micropores in ACF2 likely restricted the access of PC-solvating Li ions to the micropores. 28 The micropores of C acid and C base , constructed with short lateral size, were more accessible to the PCsolvating Li ions, promoting desolvation of the PC molecules in micropores with a size similar to the Stokes' diameter of Li þ in PC. Figure 3d illustrates the relationship between the specific capacitance and the solvation number, as well as the percentage of Li ions located in the micropores.…”
Carbon electrodes with specific microporous structures are strongly desired to improve the performance of electric double-layer capacitors (EDLCs). We report solvated states of Li ions in confined carbon micropores affecting specific capacitance. The average Li(+) solvation number of 1 M LiClO4/propylene carbonate (PC) electrolyte introduced into porous carbon electrodes was determined using Raman spectroscopy and (7)Li NMR. Micropores with slightly larger pore size against the solvated molecules and the narrow two-dimensional spaces decreased the solvation number, enhancing specific capacitance. Hence, specific carbon morphology may be related to high EDL capacitance, and micropore structure is important in obtaining highly capacitive EDLC materials.
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