We have reported for the first time a methodology to obtain the CBD internal porosity from electrochemical experiments for its use in microstructure-based electrochemical simulations of battery electrodes. Although this work has been done in the framework of positive electrodes for LIB batteries, the methodology here outlined is general to a variety of endapplications where the tortuosity factor of the electrode microstructure plays a major role in the performance, such as other battery chemistries and fuel cells. As a case study, we have used NMC111 positive electrodes with 90 %, 92 %, and 95 % active material content, aiming for porosities of 28 %, 38 %, and 48 %. We determined that samples with low electrical conductivity, i.e. for high AM content and porosity, are less useful for this determination, since they are not able to yield reliable tortuosity factor estimations. The determined values for internal CBD porosity were 0.59 ± 0.02 and 0.65 ± 0.03 for electrodes with 90 % and 92 % AM composition. However, these values are expected to depend strongly on manufacturing conditions, particularly mixing and drying conditions.