Abstract
The internal energy of capacitive porous carbon electrodes was determined experimentally as a function of applied potential in aqueous salt solutions. Both the electrical work and produced heat were measured. The potential dependence of the internal energy is explained in terms of two contributions, namely the field energy of a dielectric layer of water molecules at the surface and the potential energy of ions in the pores. The average electric potential of the ions is deduced, and its dependence on the type of salt suggests that the hydration strength limits how closely ions can approach the surface.
| Original language | English |
|---|---|
| Article number | 186001 |
| Pages (from-to) | 1-7 |
| Journal | Physical Review Letters |
| Volume | 129 |
| Issue number | 18 |
| Early online date | 28 Oct 2022 |
| DOIs | |
| Publication status | Published - 28 Oct 2022 |
Bibliographical note
Funding Information:Henkjan Siekman is thanked for making the electrochemical cell, Ties Bakker for preliminary measurements, and Bonny Kuipers, Dominique Thies-Weesie, and Alex van Silfhout for technical support. Maarten Biesheuvel is thanked for the carbon electrode material and for helpful discussions. Albert Philipse, Willem Kegel, and Andreas Härtel are thanked for helpful discussions as well. This publication is part of the project “Experimental Thermodynamics of Ion Confinement in Porous Electrodes” with Project No. 712.018.001 of the research program ECHO financed by the Dutch Research Council (NWO).
Publisher Copyright:
© 2022 American Physical Society.