A Chemical Precipitation Method Preparing Hollow–Core–Shell Heterostructures Based on the Prussian Blue Analogs as Cathode for Sodium-Ion Batteries

Prussian blue and its analogs are regarded as the promising cathodes for sodium-ion batteries (SIBs). Recently, various special structures are constructed to improve the electrochemical properties of these materials. In this study, a novel architecture of Prussian blue analogs with large cavity and multilayer shells is investigated as cathode material for SIBs. Because the hollow structure can relieve volume expansion and core–shell heterostructure can optimize interfacial properties, the complex structure materials exhibited a highly initial capacity of 123 mA h g⁻¹ and a long cycle life. After 600 cycles, the reversible capacity of the electrode still maintains at 102 mA h g⁻¹ without significant voltage decay, indicating a superior structure stability and sodium storage kinetics. Even at high current density of 3200 mA g⁻¹, the electrode still delivers a considerable capacity above 52 mA h g⁻¹. According to the electrochemical analysis and ex-situ measurements, it can be inferred that the enhanced apparent diffusion coefficient and improved insertion/extraction performance of electrode have been obtained by building this new morphology.