Optimisation of Prussian White synthesis for Sodium Ion Batteries
Alexandra Ulander
Department of Chemistry – Ångström Laboratory, Uppsala University
One of the most investigated cathode materials for Na-ion batteries are Prussian Blue
Analogues (PBAs) such as Prussian White (PW) with the approximate, ideal, composition
NaxFe[Fe(CN)6]y * zH2O, x∼2, y∼1 and z∼2. PW has emerged as one of the most interesting PBAs but there is much complexity to the material, its synthesis and its characterisation. Subsequently, the ideal composition is seldom obtained from synthesis. In this work, the influence of reducing conditions on the synthesis has been explored with the aim to obtain high quality crystals with close to ideal composition. Reducing conditions in solution is varied by change of deoxidisation of solvent and type of atmosphere. The pH, Oxidation Reduction Potential and temperature of the reaction solution is measured as a function of the reducing conditions. The material was evaluated with diffraction, SEM and Mössbauer spectroscopy to correlate the morphology, structure and composition of the material with the reducing conditions.