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.