Prussian blue analogues (PBAs) are versatile functional
materials
with numerous applications ranging from electrocatalysis and batteries
to sensors and electrochromic devices. Their electrochemical performance
involving long-term cycling stability strongly depends on the electrolyte
composition. In this work, we use density functional theory calculations
and experiments to elucidate the mechanisms of degradation of model
Na2Ni[Fe(CN)6] functional electrodes in aqueous
electrolytes. Next to the solution pH and cation concentration, we
identify anion adsorption as a major driving force for electrode dissolution.
Notably, the nature of adsorbed anions can control the mass and charge
transfer mechanisms during metal cation intercalation as well as the
electrode degradation rate. We find that weakly adsorbing anions,
such as NO3
–, impede the degradation,
while strongly adsorbing anions, such as SO4
2–, accelerate it. The results of this study provide practical guidelines
for electrolyte optimization and can likely be extrapolated to the
whole family of PBAs operating in aqueous media.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.