https://doi.org/10.1140/epje/s10189-023-00350-2
Regular Article – Soft Matter
Phase transitions of ionic fluids in nanoporous electrodes
1
Theoretical Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden
2
University College, University of New South Wales (ADFA), 2600, Canberra, ACT, Australia
Received:
13
June
2023
Accepted:
11
September
2023
Published online:
4
October
2023
In this work, we utilise grand canonical Metropolis Monte Carlo simulations, to establish pore-induced freezing of restricted primitive model fluids. A planar pore model is utilised, with walls that are initially neutral, and either non-conducting or perfectly conducting. The phase of the confined electrolyte (solid/fluid) displays an oscillatory dependence on surface separation, in narrow pores. Conditions are chosen so that the bulk is composed of a stable fluid electrolyte. The tendency for the electrolyte to freeze in narrow pores is somewhat stronger in systems with non-conducting walls. We also demonstrate that an applied potential will, above a threshold value, melt a frozen electrolyte. In these cases, the capacitance, as measured by the average surface charge density divided by the applied potential, will be almost vanishing if the applied potential is below this threshold value. We do not see any evidence for a “superionic fluid”, which has been hypothesised to generate a strong capacitance in narrow pores, due to an efficient screening of like-charge repulsions by image charges.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epje/s10189-023-00350-2.
© The Author(s) 2023
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