We propose that for carbons with smaller domains, the charges are more localized, giving rise to stronger interactions between ions and carbon atoms, thus leading to more efficient storage of ions (fig. ) . This capacity to store ions more efficiently leads to higher capacitance for 225 carbons with smaller domains, similar to previous computational studies on the correlation between capacitance and charge compensation per carbon . We further hypothesize that the smaller domains may be connected with a higher concentration of topological defects (edge sites, pentagonal and heptagonal rings, curvature), which were previously suggested to increase capacitive performance . Indeed, previous studies of hard carbons for sodium ion batteries found a 230 more favorable interaction of sodium ions with edge sites and defects compared to basal planes of graphene-like fragments , with the latter paper ascribing the sloping voltage seen in these systems to a pinning of the inserted electrons by the carbon defects . Finally, while previous studies suggested that carbon-ion distances decrease due to desolvation , we hypothesize that defects may drive the denser packing of ions in the carbon pores . 235