Hierarchical Octahedral Na2MnFe(CN)6 and Na2MnFe(CN)6@Ppy as Cathode Materials for Sodium-Ion Batteries

The Na2MnFe(CN)(6) is successfully synthesized by a simple co-precipitation method, and then coated with conducting polymers (PPy) on the surface of Na2MnFe(CN)(6) particle. Interestingly, Na2MnFe(CN)(6) and Na2MnFe(CN)(6)@PPy both show hollow octahedral hierarchical structures with nanometer-sized subunits. Na2MnFe(CN)(6)@PPy exhibits a discharge capacity of 107 mAh center dot g(-1) after 150 cycles at a current density of 10 mA center dot g(-1). It can still remain 65 mAh center dot g(-1) even the current density is increased to 200 mA center dot g(-1). This superior electrochemical property could be ascribed to unique hierarchical architecture as well as improved electronic conductivity.