ure ), we examine the local cation diffusivities from MD simulations (Figure ), which serve as the input for cation hopping rates in the on-lattice kMC model. At higher particle loadings, the nanoparticles approach each other more closely (SI, Section S5.1) resulting in an overlap between the surface sites of neighboring particles (see Figure ). The cation mobilities in the overlapping surface region are significantly reduced compared to those in the non-overlapping surface region (Figure ). This reduction can be attributed to the combined effect of increased anion-cation electrostatic interactions (SI, Section S5.4) and increased steric hindrance effects due to higher number density of tethered polymer chains and anions in the overlapping surface region (SI, Section S1.1). At higher particle loadings, due to significant cation presence on overlapping surface sites (SI, Section S5.5), the increased connectivity of surface sites is countered by the slower cation transport in the overlapping surface regions, leading to a decrease in D cat and conductivity with φ. To support this mechanistic interpretation, we repeated the kMC calculations for a fictitious case with D values in the overlapping surface region set equal to those in the non-overlapping surface region.