Preparation of K2Fe[Fe(CN)6] nanoparticles by improved electrostatic spray assisted precipitation technology as potassium-ion battery cathodes

Prussian blue analogues, which have a stable structural framework and larger ion migration channels, are currently one of the most potential cathodes for potassium ion batteries. However, Prussian blue-based materials are susceptible to preparation conditions, resulting in vacancy defects and crystal water in structures, which seriously restricts the exertion of electrochemical properties. Herein, a novel preparation technology-an electrostatic spray assisted coprecipitation way protected by inert atmosphere is proposed and applied to the synthesis of K2Fe[Fe(CN)6] materials. The effects of preparation process on the crystallinity, microstructure and potassium storage performances of K2Fe[Fe(CN)6] are systematically discussed. The results prove that K2Fe[Fe(CN)6] synthesized by the new preparation process has good crystallinity (K1.56Fe[Fe(CN)6]0.89·□0.11·1.86 H2O), small particle size (~20 nm) and high specific surface area (104.31 m2 g−1), and finally exhibits excellent electrochemical performance, including an superb cycling stability of 89 mAh g−1 after 503 cycles at 0.5 C and rate capability of 82 mAh g−1 at 10 C. In addition, this preparation technology also provides a new strategy for the microstructure and performance optimization of other Prussian blue-based materials.