Double-Shelled Ni-Fe-P/N-Doped Carbon Nanobox Derived from a Prussian Blue Analogue as an Electrode Material for K-Ion Batteries and Li-S Batteries

Rational design, convenient fabrication, and application of double-shelled hollow architectures with well-defined morphology and multicompositions as electrodes for rechargeable batteries still remain great challenges. Herein, double-shelled Ni-Fe P/N-doped carbon nanoboxes (defined as Ni-Fe-P/NC) were synthesized and then applied as electrode materials for potassium ion batteries (KIBs) and Li-S batteries, first. The unique architectures could not only alleviate volume changes and prevent aggregation of Ni-Fe-P/NC during cycling but could also provide efficient surface areas for infiltration of electrolyte. Additionally, nitrogen-doped carbon could improve the conductivity of the electrode. Hence, when these Ni-Fe-P/NC nanoboxes were applied as anode materials for KIBs, they delivered enhanced cycling stability (172.9 mA h g(-1) after 1600 cycles at 500 mA g(-1) and 115 mA h g(-1) after 2600 cycles at 1000 mA g(-1)). Meanwhile, the Ni-Fe-P/NC could also be used as the sulfur host material for Li-S batteries; benefiting from its unique hollow structure, it can accommodate high sulfur loading and have strong chemical adsorption ability to polysulfides.