Figure 17.

Models for CapMix devices. (A) A full device consists of two macroscopic porous electrodes maintained at different potentials. Inside each electrode, the confined fluid can exchange particles with the bulk electrolyte reservoir, and the exchange of ions leading to charge storage occurs mainly in nanopores. Reproduced with permission from ref (304). Copyright 2015 IOP Publishing. (B) Two standard approaches used in the contexts of CapMix and CDI (see text for more details): GCS theory and modified Donnan (mD) model, thought to apply better in the limits of nonoverlapping and overlapping electric double layer regimes, respectively. The lines represent the potential distribution at the interface or inside the pore. cDFT can provide a more accurate description of the ionic and potential distribution in the same model geometries, including at larger concentrations. Adapted with permission from ref (299). Copyright 2015 Royal Society of Chemistry under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/). (C) Molecular simulation of a capacitor consisting of two nanoporous carbon electrodes maintained at a constant potential difference and a 1 M aqueous NaCl solution (top). The charge of each electrode atom fluctuates (color scale in the middle part of the panel) in response to the instantaneous microscopic configuration of the electrolyte (bottom). Reproduced with permission from ref (305). Copyright 2018 American Physical Society under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).