Hello everyone,
I am running simulations in ConductoDict using a solid material for the active material of my battery, and porous material for the carbon-binder-domain. How does the porosity of this porous material influence the conductivity results? Because so far, I get the same overall conductivity results no matter if I use a solid or porous CBD, when I manually insert the same intrinstic conductivity value. I thought I would get lower conductivities if my CBD is porous (e.g. 50 percent), as my overall structure thus contains more parts with low-conductive air. In other words, I though that the "solid" part of my porous CBD would adopt the conductivity that I manually enter and the air inside the porous material would adopt the same intrinsic conductivity as the air or electrlyte surrounding the CBD and active material. It seems like I am wrong. What difference does it make for conductivity simulations to have a porous material or a solid material, if the results are always the same?
Best,
Caroline
Dear Caroline,
the conductivity of the porous material depends on the selected Mixing Rule. If you select Single Phase, you must enter the effective conductivity of the porous material as input. If you select a specific Mixing Rule, the conductivity of the porous material is approximated with a simple formula from the conductivity of the solid material and the fluid material.
See this user guide page, under the Porosity/Tortuosity toggle:
https://geodict-userguide.math2market.de/2025/conductodict_computethermalconductivity_constituentmaterials.html
Best regards,
Jürgen
Hello Jürgen,
thank you very much, for this quick response. I understand what you mean, and this is exactly what I want. The only thing is, that I don't have this option to check "Has Tortuosity", because I don't have the tab "Porosity/Tortuosity" when I want to compute conductivity. Do I need to active something before? I only have the tabs "Electrical conductivity" and "Specific Electrical Contact Resistivity" when I open the Edit-window for setting up the simulation, even when I use porous materials. I have GeoDict 2024, is that too old for this feature? Or do I have to change something in the material database? I already set the material to porous and gave it a porosity of 50 % and a certain tortuosity. Everything looks exactly as on the website you sent me, but I am missing this one tab.
Best,
Caroline
Yes, this feature was added in GeoDict 2025.
In the 2024 version, it is always Single Phase mode.
Best regards,
Jürgen
I understand. Thank you very much for the quick replies.
Best regards,
Caroline