Double-Coated Fe2N@TiO2@C Yolk-Shell Submicrocubes as an Advanced Anode for Potassium-Ion Batteries†

Main observation and conclusion Rationally designing inexpensive iron nitrides that have large conductivity, high theoretical capacity, and rapid ionic diffusion kinetics is of great importance for realizing their practical application in potassium-ion batteries. In this work, we have constructed double-shelled Fe2N@TiO2@C yolk-shell submicrocubes with porous Fe2N yolk as an anode material for stable and high-rate capability potassium-ion batteries. This special structure can effectively buffer the large volume variation of electrode during cycling, supply abundant reaction sites to host potassium ions, and enhance electronic conductivity of the electrode material. Benefiting from these structural and compositional advantages, the Fe2N@TiO2@C yolk-shell submicrocube anode delivers high specific capacity, long-term cyclability, and remarkable rate property.