Iron Nitride@C Nanocubes Inside Core-Shell Fibers to Realize High Air-Stability, Ultralong Life, and Superior Lithium/Sodium Storages.

Poor air stability and severe structure pulverization are crucial issues for metal nitrides in metal-ion batteries. Herein, core-shell hybrid fibers (CSHN fiber) filled with metal nitride@C hollow nanocubes are introduced to be a new self-supporting anode for sodium-ion and lithium-ion batteries. The hierarchical carbon network provides fast electronic pathways and gives high protection for iron nitrides. Meanwhile, the self-supporting electrode avoids the complicated electrode fabrication process and decreases the opportunity to air exposure. Moreover, its porous nature ensures high buffer to volumetric expansion and improves the cycling stability. Therefore, it is a good platform to realize fast kinetics and high durability. For the first time, Fe2N@N-doped carbon CSHN hybrid fibers are constructed. Their influences on air stability and electrochemical behaviors are studied. Impressively, they achieve high stabilities in both lithium-ion (92.8%, at 5 A g-1, 1000 cycles) and sodium-ion (95.6%, at 2 A g-1, 2000 cycles) batteries. Therefore, this work introduces a new method to construct superior performance nitride anodes. Moreover, it also provides a new insight on the fabrication of highly efficient structures for diverse functional materials.