On the one hand, the size of the Si particles we used (300 nm) is larger than the experimental one, since commercial Si nanoparticles range between 40 and 70 nm in diameter. This assumption is justified by the fact that Si nanoparticles hardly ever disperse perfectly in the dry electrode. Instead, they tend to form aggregates . Additionally, this assumption allows us to build a model with a reasonable number of particles, given our computational resources. Figure shows a preliminary calculation of the number of Si particles to be simulated as a function of the targeted simulation box volume and Si particles size, given the aforementioned formulation. As shown, the number of particles quickly rises when considering smaller Si particles, calling for a compromise between microstructural representativeness and the computational cost (which links to the total number of particles). This compromise is met by selecting a target volume of 30×30×30 μm 3 (even though, the exact final equilibrated volume will depend on the FF parameters) and a Si particle diameter of 300 nm, which results in system that contains ~90000 particles. Even if the Si particles where considered as n-Si aggregates in this work, we must note that a diameter of 300 nm is still a higher limit for the resistance to fracture upon volume expansion .