Porous Electrode
The Porous Electrode node sets up current balances for a porous electrode matrix and a pore electrolyte, as well as the mass balance for the pore electrolyte in a domain. The node may also set up a mass balance of an intercalating species in the electrode particles. By addition of Porous Electrode Reaction subnodes, the feature is also able to define the charge transfer reactions that take place at the interface between the pore electrolyte and the porous electrode matrix. A Porous Matrix Double Layer Capacitance and a Porous Matrix Adsorption/Desorption Reaction (for the Battery with Binary Electrolyte interface), can also be added to the node.
Use correction factors to account for the lowered diffusion coefficients in the electrolyte and the lowered conductivities of the electrode, due to the lower volume fractions of each phase and the tortuosity of the porous matrix.
See also the Electrolyte and Electrode nodes for more information about the settings of this node.
Electrolyte Properties
See the Electrolyte node for more information about the settings of this section.
Electrode Properties
See the Electrode node for more information about the settings of this section
Particle Properties
By selecting Intercalating particles, the node adds a mass balance and the corresponding dependent variables for solving for an intercalating concentration. The settings related to the intercalation are set on the Particle Intercalation child node.
Porous Matrix properties
The Electrode volume fraction εs and Electrolyte volume fraction ε1 parameters are used in the mass balance equations to account for the available volume of each phase, and also in the Porous Electrode Reaction to calculate the surface area. These parameter values may also be used by the Effective Transport Parameter Correction (next section). Similarly, the Electrode tortuosity τs and Electrolyte tortuosity τ1 parameters may also be used by the Effective Transport Parameter Correction (next section).
Effective Transport Parameter Correction
Use the settings of this section to calculate effective transport parameters for the electrode and the electrolyte if your corresponding parameter values refer to nonporous media.
Dissolving-Depositing Species
Use the settings of this section to define species that participate in dissolution-deposition electrode reactions within the porous electrode, for instance, metal deposition/dissolution or oxide formation.
Use the Add () and Delete () buttons as needed in the tables to control the number of species.
Dependent variables for the volumetric molar concentration are added for each dissolving-depositing species. These variables can be used to keep track of the amount of reacted material in the porous electrode. The total molar dissolution/deposition rate depends on the reaction rates and stoichiometry, defined in the Porous Electrode Reaction subnodes.
The Density and Molar mass determine the electrode growth velocity and the resulting dissolved/deposited layer thickness. By multiplying by the electrode surface area (in the case of multiple electrode reaction the average surface area is used), the change in electrode and electrolyte volume fractions can be also be calculated. By use of the Add volume change to electrode volume fraction (not available for Separator node) and Subtract volume change from electrolyte volume fraction check boxes you may define how these volume changes should be included in the model.
Thickness variables, based on the surface area, are also defined that you for instance can use to couple to the Film Resistance (see below).
FILM RESISTANCE
A film resistance is typically used for modeling the build-up of a SEI (solid electrolyte interface) layer in lithium-ion battery graphite electrodes. See also the Electrode Surface node.