The morphological properties of the S/C electrode in Li-S batteries are composed of multiple phases and vary over multiple length scales. Figure shows the reconstructed S/C pristine electrode and the detailed orthoslice, both of which show the S/C cathode consisting of three phases: elemental sulfur, CBD and electrolyte (which fills the pores), segmented based on the greyscale attenuation factor. Figure ) shows the volume of Sulfur (yellow), pores filled with electrolyte (pink), and CBD (grey) present in the S/C electrode and highlights the complex and heterogeneous 3D nature of the phase distribution in the electrode. Figure and) show the coloured spatial distribution of sulfur particle size and pore sizes, respectively. Each colour represents different size particles (e) and pores (f), highlighting the extent of heterogeneity present in the electrode microstructure. As experimentally observed by various researchers, the heterogeneity of the particle affects the rate of sulfur dissolution, i.e., dissolution of solid sulfur (S8(solid)) into the electrolyte . In the modelling approach presented here, the starting point is to assume that all the sulfur (dissolved and not dissolved in the electrolyte) is in the liquid phase, the solid morphology change of sulfur will not be considered, so while this contribution to the effects of heterogeneity on performance is not captured in the 3D model, it is important to note its effect in real electrodes. In Li-S battery electrodes, the pores in both the cathode and the separator are filled with an aprotic electrolyte, typically 1M LiTFSI and 0.8% LiNO3 dissolved in dimethoxyethane (DME):1,3-dioxolane (DOL) in 1:1 volume ratio, as are the pores within the CBD carbon itself .