for high CBD internal porosity and 2.0 for low CBD internal porosity. This can be interpreted in light of the method used for the addition of the binder material on the microstructure: when the CBD is compact, it is placed joining pairs of AM particles, and acts almost as a wall for diffusion. This results in a network of spheres, joined by low diffusivity cylinders with low aspect ratio. This recalls the model situation resulting in 𝜶 = 𝟐. 𝟎. On the other side, when CBD is spread out and very permeable, it occupies a large fraction of the available space, where ion diffusivity follows equation ( ) with a value of 𝜶 = 𝟏. 𝟓.