Engineering flexible carbon nanofiber concatenated MOF-derived hollow octahedral CoFe2O4 as an anode material for enhanced lithium storage

Abstract

Constructing suitable electrode materials with high capacity and excellent mechanical properties is indispensable for flexible lithium-ion batteries (LIBs) to satisfy the growing requirements of flexible and wearable electronic devices. Herein, a necklace-like architecture of metal–organic framework (MOF)-derived hollow octahedral CoFe₂O₄ confined into electrospun one-dimensional N-doped carbon nanofibers (CoFe₂O₄@CNFs) is successfully developed. The hollow structure not only provides space to accommodate the volumetric expansion of the CoFe₂O₄ nanoparticles, but also shortens the Li⁺ diffusion length. Furthermore, the CNF-supported three-dimensional conductive framework can effectively prevent CoFe₂O₄ particle agglomeration and pulverization for enhanced structural stability, and meanwhile promote the diffusion of electrons in all directions, thus enhancing the reaction kinetics. Owing to the unique structure characteristics, the free-standing CoFe₂O₄@CNF anode for LIBs exhibits a reversible capacity of 1230 mA h g⁻¹ at 0.1 A g⁻¹ and superior cycling stability (735.1 mA h g⁻¹ at 0.5 A g⁻¹ over more than 500 cycles). Interestingly, the CoFe₂O₄@CNF films also exhibit impressive mechanical performance and remarkable flexibility, demonstrating their great potential for application in flexible energy storage devices.