Potassium (De-)insertion Processes in Prussian Blue Particles: Ensemble versus Single Nanoparticle Behaviour

Potassium (de-)insertion from Prussian blue (PB) is investigated at the single and multi-particle scale. The electrochemical behaviour is found to differ between the two measurement types. At the single particle level, oxidation of the PB nanoparticles with concomitant K⁺ deinsertion occurs more readily than the associated reduction, relating to K⁺ insertion. In contrast, the cyclic voltammetry of PB in a composite electrode containing conductive additives and polymeric binder suggests the opposite behaviour. Implications for assessing battery materials are discussed.