Core–shell CuFeMnHCF@CuHCF: a high-rate and durable Prussian blue cathode for sodium-ion batteries

Abstract

A core–shell CuFeMnHCF@CuHCF composite was prepared via a continuous one-pot co-precipitation and ion exchange method. The monoclinic Cu-doped FeMnHCF core and the cubic Cu₂Fe(CN)₆ shell can mitigate Jahn–Teller distortion and suppress Mn dissolution. This synergy enables superior rate capability and 79.0% capacity retention after 400 cycles, with in situ XRD revealing a reversible monoclinic ↔ cubic transition.