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Item type:Publication, Access status: with files , Temperature-dependent capacitance of the electrical double layerWe use atomistic simulations to study the electrical double layer (EDL) at an electrode–electrolyte interface at different temperatures. For a constrained electrode charge, the potential drop over the EDL increases with temperature, a phenomenon known as the thermal voltage rise (TVR). Prior continuum models attributed TVR to expansion of the EDL with increasing temperature; conversely, our simulations with aqueous, organic, and ionic liquids show that the EDL does not expand but that the TVR is caused by a decrease in interfacial permittivity with increasing temperatures.Publicationtype: Journal Article57 60 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Water, not salt, causes most of the Seebeck effect of nonisothermal aqueous electrolytes(American Physical Society (APS), 2024-05-03); ; ; A temperature difference between two electrolyte-immersed electrodes often yields a voltage Δψ between them. This electrolyte Seebeck effect is usually explained by cations and anions flowing differently in thermal gradients. However, using molecular simulations, we found almost the same Δψ for cells filled with pure water as with aqueous alkali halides. Water layering and orientation near polarizable electrodes cause a large temperature-dependent potential drop χ there. The difference in χ of hot and cold electrodes captures most of the thermovoltage, Δψ≈χhot-χcold.Publicationtype: Journal Article11 83 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , ELECTRODE: an electrochemistry package for atomistic simulations(American Institute of Physics (AIP), 2022-08-25); ; ; Constant potential methods (CPM) enable computationally efficient simulations of the solid-liquid interface at conducting electrodes in molecular dynamics (MD). They have been successfully used, for example, to realistically model the behavior of ionic liquids or water-in-salt electrolytes in supercapacitors and batteries. The CPM models conductive electrodes by updating charges of individual electrode atoms according to the applied electric potential and the (time-dependent) local electrolyte structure. Here we present a feature-rich CPM implementation, called ELECTRODE, for the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), which includes a constrained charge method and a thermo-potentiostat. The ELECTRODE package also contains a finite-field approach, multiple corrections for non-periodic boundary conditions of the particle-particle particle-mesh solver, and a Thomas-Fermi model for using non-ideal metals as electrodes. We demonstrate the capabilities of this implementation for a parallel-plate electrical double-layer capacitor, for which we have investigated the charging times with the different implemented methods and found an interesting relationship between water and ionic dipole relaxations. To prove the validity of the one-dimensional correction for the long-range electrostatics, we estimated the vacuum capacitance of two co-axial carbon nanotubes and compared it to structureless cylinders, for which an analytical expression exists. In summary, the ELECTRODE package enables efficient electrochemical simulations using state-of-the-art methods, allowing one to simulate even heterogeneous electrodes. Moreover, it allows unveiling more rigorously how electrode curvature affects the capacitance with the one-dimensional correction.Publicationtype: Journal ArticleScopus© Citations 19 201 530