Synergistic Modification of Fe-Based Prussian Blue Cathode Material Based on Structural Regulation and Surface Engineering

Authors：Chen, Zhao-Yao; Zhang, Lu-Lu^*; Fu, Xin-Yuan; Yan, Bo; Yang, Xue-Lin^*

Source：ACS applied materials & interfaces, 2022, 14(38): 43308-43318.

DOI：10.1021/acsami.2c11823

• sodium-ion battery
• cathode material
• Fe-based Prussian blue
• synergistic modification
• Cu doping
• CuO coating

The Fe-based Prussian blue (Fe-PB) composite is considered as one of the most potential cathode materials for sodium-ion batteries because of its abundant iron resources and high theoretical capacity. However, the crystal water and vacancy in the Fe-PB structure will lead to poor capacity and cycle stability. In this work, a Cu-modified Fe-PB composite (FeCu-PB@CuO) is successfully prepared through regulating the Fe-PB structure by Cu doping and engineering the surface by CuO coating. The density functional theory calculation results confirm that Cu preferentially replaces Fe(HS )in the Fe-PB lattice and Cu doping reduces the bandgap. Our experiment results reveal that CuO coating can provide more active sites, inhibit side reactions, and potentially enhance the activity of Fe-HS. Due to the synergistic effect of Cu doping and CuO coating, FeCu-PB@CuO has a considerable initial discharge capacity of 123.5 mAh g(-1) at 0.1 A g(-1). In particular, at 2 A g(-1), it delivers an impressive initial capacity of 84.3 mAh g(-1), and the capacity decreasing rate of each cycle is only 0.02% over 1500 cycles. Therefore, the synergistic modification strategy of metal ion doping and metal oxide coating has tremendous application potential and can be extended to other electrode materials.