Iron-based Prussian blue coupled with polydopamine film for advanced sodium-ion batteries

Abstract

In this study, high-performance polydopamine (PDA) coated Na1.33FeFe(CN)6·1·16H2O (PBA) cathode materials for sodium-ion batteries (SIBs) are successfully synthesized by using a single source method with Na4Fe(CN)6 as sole iron source. The PDA coating does not alter the structure or morphology of the PBA sample, but greatly improves its conductivity and Na ion diffusion ability because of the good conductivity. Consequently, we observe enhanced reversible capacity, rate capability and cycle stability during cycling. Our results indicate that PBA-2 has the best electrochemical performance and sodium ion diffusion coefficient among all samples. Even at 1 C rate, PBA-2 has a high initial discharge capacity of 145 mAh g−1 with a capacity retention of 90% over 100 cycles. The introduction of a suitable amount of PDA represents an effective strategy for enhancing the electrochemical activity of PBA for advanced SIBs. Such design strategies can be also used to modify other cathode materials for SIBs.