The number of nanoparticles considered for the microstructures in the dataset should be large enough to capture the wide variety of possible topologies spanning length scales relevant for cation transport. At the same time, the microstructures should be small enough such that the ground truth diffusivities for a large number of distinct particle configurations can be calculated at a reasonable computational cost. In our study, we balance these considerations by using configurations of N = 91 identical nonoverlapping nanoparticles of diameter σ NP in a cubic box of size L with periodic boundary conditions. The nanoparticle volume fraction N πσ NP /(6L 3 ) is fixed to be 0.1 for all the structures. Such a choice of volume fraction allows for realizing a variety of nanoparticle configurations exhibiting broad range of cation diffusivities.