where σeff is the effective conductivity of the composite and σ1,2 and Φ1,2 are the conductivities and volume fractions of phase 1 and 2, respectively. Porosity is not specifically considered as third phase in this study, the effect of which is expected to be negligible given constant degrees of porosity between all composites in first approximation. The parameter k is a constant that describes the connectivity of the phases within the composite and determines the percolation threshold. Subsequently, the data have been fit by solving Eq. 5 for σeff and using k and the conductivity of the better conducting phase (σe,CAM for σe and σion,SE for σion) as fitting constants. With that, the experimental results of both conductivities can be well described (dashed lines in Figure ) allowing to approximate the effective transport between and closely surrounding the investigated compositional space of the cathode. The final fitting equation σeff(σ1, σ2, Φ1, Φ2, k), the resulting fitting constants and details of the procedure are given in the Supporting Information. Importantly, the effective medium model does not account for any interfacial effects between both phases, or grain boundary transport/resistance that can explain uncertainties deviation between fit and data.