We report a comparison of different common synthetic strategies for preparation of Prussian blue analogues (PBA). PBA are promising as cathode material for a number of different battery types, including K-ion and Na-ion batteries with both aqueous and non-aqueous electrolytes. PBA exhibit a significant degree of structural variation. The structure of the PBA determines the electrochemical performance, and it is, therefore, important to understand how synthesis parameters affect the structure of the obtained product. PBA are often synthesized by co-precipitation of a metal salt and a hexacyanoferrate complex, and parameters such as concentration and oxidation state of the precursors, flow rate, temperature and additional salts can all potentially affect the structure of the product. Here, we report 12 different syntheses and compare the structure of the obtained PBA materials.

In this work, we investigate factors affecting the capacity retention of aqueous copper hexacyanoferrate/Zn batteries. We compare the performance of four different copper hexacyanoferrate (CuHCF) samples as cathode in CuHCF/Zn cells with Na2SO4 and ZnSO4 based electrolytes at different pH. In Na2SO4 electrolyte, the capacity retention is improved at lower pH, whereas cells with ZnSO4 electrolyte perform similarly at pH 2 and 4. Finally, we show that the performance of CuHCF/Zn cells is highly dependent on the CuHCF sample, underlining the necessity for detailed synthesis description and thorough structural characterization of electrode materials.