The Porous Electrode node sets up charge balances for the electrode and the pore electrolyte in a porous electrode. Note that the node should be used for porous domains that conduct current in both an electrolyte and an electrode phase. For the case of domains that do not contain a pore electrolyte — for instance, the gas diffusion layer (GDL) in a PEMFC electrode — use an Electrodenode instead.

Use Porous Electrode Reaction subnodes to define the charge transfer reactions that occur on the interface between the electrolyte and electrode phases within the porous electrode. For the Secondary Current Distribution interface, the Porous Matrix Double Layer Capacitance subnode is also available.

The conductivities are taken From material by default. From the respective material list you may any material in the model, if present. By default they are set to the Domain material (which is the material applied to the active domain in the Materials node).

You may use the Effective conductivity correction factors to account for the lowered effective conductivities of the electrode and electrolyte phases due to the lower volume fractions of each phase, and the tortuosity of the porous matrix.

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 and Subtract volume change from electrolyte volume fraction check boxes you may define how these volume changes should be included in the model.

See the Electrode Surface node.