Confined Fe2VO4⊂Nitrogen‐Doped Carbon Nanowires with Internal Void Space for High‐Rate and Ultrastable Potassium‐Ion Storage

Abstract Developing low‐cost, high‐capacity, high‐rate, and robust earth‐abundant electrode materials for energy storage is critical for the practical and scalable application of advanced battery technologies. Herein, the first example of synthesizing 1D peapod‐like bimetallic Fe 2 VO 4 nanorods confined in N‐doped carbon porous nanowires with internal void space (Fe 2 VO 4 ⊂NC nanopeapods) as a high‐capacity and stable anode material for potassium‐ion batteries (KIBs) is reported. The peapod‐like Fe 2 VO 4 ⊂NC nanopeapod heterostructures with interior void space and external carbon shell efficiently prevent the aggregation of the active materials, facilitate fast transportation of electrons and ions, and accommodate volume variation during the cycling process, which substantially boosts the rate and cycling performance of Fe 2 VO 4 . The Fe 2 VO 4 ⊂NC electrode exhibits high reversible specific depotassiation capacity of 380 mAh g −1 at 100 mA g −1 after 60 cycles and remarkable rate capability as well as long cycling stability with a high capacity of 196 mAh g −1 at 4 A g −1 after 2300 cycles. The first‐principles calculations reveal that Fe 2 VO 4 ⊂NC nanopeapods have high ionic/electronic conductivity characteristics and low diffusion barriers for K + ‐intercalation. This study opens up new way for investigating high‐capacity metal oxide as high‐rate and robust electrode materials for KIBs.