Pseudocapacitive Trimetal Fe 0.8 CoMnO 4 Nanoparticles@Carbon Nanofibers as High‐Performance Sodium Storage Anode with Self‐Supported Mechanism

Trimetal Fe 0.8 CoMnO 4 (FCMO) nanocrystals with a diameter of about 50 nm perfectly embedded in N doped‐carbon composite nanofibers (denoted as FCMO@C) are successfully prepared through integrating double‐nozzle electrospinning with a drying and calcination process. The as‐prepared FCMO@C nanofibers maintain a high reversible capacity of 420 mAh g −1 and about 90% capacity retention after 200 cycles at 0.1 A g −1 . For a long‐term cycle, the FCMO@C electrode exhibits excellent cycling stability (87% high capacity retention at 1 A g −1 after 950 cycles). Kinetic analysis demonstrates that the electrochemical characteristics of the FCMO@C corresponds to the pseudocapacitive approach in charge storage as an anode for sodium ion batteries, which dominantly attributes the credit to FCMO nanocrystals to shorten the migration distance of Na + ions and the nitrogen‐doped carbon skeleton to enhance the electronic transmission and favorably depress the volume expansion during the repeated insertion/extraction of Na + ions. More significantly, a self‐supported mechanism via continuous electrochemical redox reaction of Fe, Co, and Mn can effectively relieve the volume change during charge and discharge. Therefore, this work can provide a new avenue to improve the sodium storage performance of the oxide anode materials.