High-rate sodium storage performance enabled using hollow Co3O4 nanoparticles anchored in porous carbon nanofibers anode

Abstract Transition metal oxides with high theoretical specific capacity, when used as anode materials in sodium-ion batteries, usually suffer from poor structural stability and inferior rate capacity. The use of hollow nanostructured metal oxides incorporated into porous carbon frameworks is a promising strategy for addressing this issue. Herein, we fabricated hollow Co3O4 nanoparticles anchored in a porous carbon nanofiber matrix (Co3O4@PCNF) by electrospinning, metal–organic framework incorporation, and two-step calcination. The porous carbon nanofiber matrix can facilitate structural stability and provide multiple channels for fast electron/ion transport. The hollow Co3O4 nanoparticles resulting from the Kirkendall effect can shorten the Na-ion transport path for achieving fast reaction kinetics. The Co3O4@PCNF exhibits a reversible specific capacity of 487 mAh g-1 at 0.05 A g-1 with a high initial Coulombic efficiency of 91.6%, outstanding rate performance (220 mAh g-1 at 5 A g-1), and stable cycling, thereby making it suitable as an anode for sodium-ion batteries. Moreover, a full cell fabricated using a Co3O4@PCNF anode and Na3V2(PO4)2O2F cathode delivers a reversible capacity of 205 mAh g-1 at 0.5 A g-1. We believe that our approach can provide a design pathway to improve the performance of Co3O4-based anodes for sodium-ion batteries and offer a new strategy to produce hollow-structure electrode materials for other energy-storage devices.