Flexible electrospun FeCo/carbon hybrid nanofiber films as binder-free anodes for enhanced lithium storage performance.

• The flexible FeCo@NFM was prepared by simple electrospinning method. • Small FeCo nanoparticles (∼10 nm) are uniformly encapsulated in the CNFs. • The as-prepared FeCo@NFM is directly used as a binder-free electrode. • The hierarchical structure can greatly promote Li+ insertion/extraction kinetics. • The electrode exhibits high capacity, good rate capability and cycling stability. The design of electrodes with excellent mechanical elasticity is the significant to developing flexible electronic devices with mechanical endurance and outstanding lithium storage properties. Herein, the flexible FeCo/carbon hybrid nanofiber membranes (named as FeCo@CNFM) were successfully prepared via electrospinning and subsequent carbonization process. From the macroscopic perspective, the FeCo@CNFM can bend at a large angle without any destruction, and be directly used as working electrode of lithium ions batteries (LIBs) without any expensive additives, demonstrating its extraordinary mechanical flexibility. From the microscopic perspective, the homogeneously dispersed fine FeCo nanoparticles and the three-dimensional (3D) interconnected transport network constructed of carbon nanofibers significantly shorten the lithium-ion transfer distance, eliminate the volume fluctuation during lithiation/delithiation process, enhance the utilization rate of active materials, and promote the electrical conductivity of the composite electrode, thus leading to remarkably improved electrochemical properties. As a consequence, the optimized FeCo@CNFM manifests a superior discharge capacity of 584.9 mA h g−1 at 100 mA g−1 after 100 cycles with long cycling stability and good rate capability of 227.1 mA h g−1 even at a large current rate of 2 A g−1, making it a promising flexible self-supporting anode for LIBs. [Display omitted] [ABSTRACT FROM AUTHOR]