Combined in situ scattering and modelling approach published in Nature Energy
The novel method presented in this work combines in situ small angle X-ray scattering (SAXS) and Monte Carlo simulation techniques to quantify local ion rearrangement and partial ion desolvation inside a nanoporous carbon based supercapacitor. Conclusively the ion arrangement in pore sites with different degree of confinement could be related to the degree of electrode charge localization and the macroscopic capacitive performance.
This work was carried out in collaboration with the Energy Materials Group (INM Saarbrücken), the Austrian SAXS Beamline (TU Graz, Synchrotron ELETTRA, Trieste) and the Computational Physics Group at the University of Vienna.
The paper “Quantification of ion confinement and desolvation in nanoporous carbon supercapacitors with modelling and in situ X-ray scattering” was published in Nature Energy.
Link to the publication: https://www.nature.com/articles/nenergy2016215
Link to online version of the paper: http://rdcu.be/oVTP
A detailed understanding of confinement and desolvation of ions in electrically charged carbon nanopores is the key to enable advanced electrochemical energy storage and water treatment technologies. Here, we present the synergistic combination of experimental data from in situ small-angle X-ray scattering with Monte Carlo simulations of length-scale-dependent ion arrangement. In our approach, the simulations are based on the actual carbon nanopore structure and the global ion concentrations in the electrodes, both obtained from experiments. A combination of measured and simulated scattering data provides compelling evidence of partial desolvation of Cs + and Cl ? ions in water even in mixed micro–mesoporous carbons with average pore size well above 1?nm. A tight attachment of the aqueous solvation shell effectively prevents complete desolvation in carbons with subnanometre average pore size. The tendency of counter-ions to change their local environment towards high confinement with increasing voltage determines conclusively the performance of supercapacitor electrodes.