Mn-HCF@Fe-HCF Core-Shell Architecture: Enhancing Structural Stability and Electrochemical Performance of Sodium-Ion Batteries

To overcome the structural failure of Manganese-based Prussian blue analogue (Mn-HCF) as a cathode material of sodium ion batteries caused by Mn ion dissolution induced by Jahn-Teller effect, we coated Mn-HCF with iron-based Prussian blue (Fe-HCF) to prepare the core-shell Mn-HCF@Fe-HCF cathode material for sodium ion batteries through co-precipitation method. The research results indicate that this structure effectively blocks the direct contact between Mn-HCF and electrolyte, thereby minimizing the dissolution of Mn3+ in the electrolyte and significantly improving the cycling stability and rate performance. The discharge capacity of this material at a current density of 0.1C (14mAg(-1)) is 129.7mAhg(-1). It still has a capacity of 87.4mAhg(-1) at a current density of 2C (280mAg(-1)), and still has a capacity retention rate of 84.3% (91mAhg(-1)) after 100 cycles at a current density of 0.5C (70mAg(-1)). Compared with the capacity retention rate of 51.5% of Mn-HCF 100 cycles before coating, the cycle stability of Mn-HCF@Fe-HCF is greatly improved.