Having established a parallel between the reactivity trends of chloride and fluoride catholytes, we compare their stability against sulfide and oxide anolytes in terms of predicted ∆H values. Differences in ∆H values for fluoride and chloride catholytes are governed almost entirely by two main contributions: (i) On the product side of Eq. 1: the difference in FEs between LiCl and LiF. (ii) On the reactant side: the difference in FEs between Li i MCl j and Li i MF j . The FEs of LiF and Li i MF j compounds are more negative than their chloride analogs, which is justified by the higher electronegativity of fluorine (∼3.98 according to the Pauling scale) compared to chlorine (∼3.16). Since LiF is a reaction product, its more negative FE makes the ∆H values of fluoride catholytes more negative (lower) -i.e., the reaction is more thermodynamically favorable-as compared to chlorides. On the other hand, the more negative FE of Li i MF j increases their ∆H (more positive values) compared to their chloride analogs. The competing effects of the more negative FEs of LiF and Li i MF j regulate the propensity to decompose fluoride-based bilayer separators. We find that only Li 3 InF 6 -based bilayers have more negative ∆H values (making it less stable) as compared to Li 3 InCl 6 -based bilayers (Figure ). All other fluoride-based bilayers considered here have more positive ∆H values than their chloride analogs, making them more stable.