Well-dispersed FeNi nanoparticles embedded in N-doped carbon nanofiber membrane as a self-supporting and binder-free anode for lithium-ion batteries

Abstract

Flexible energy storage systems and wearable electronics are revolutionary and prospective technologies for various photoelectronic equipment. Herein, a three-dimensional (3D) nanoarchitecture of N-doped carbon nanofibers (NCNFs) with in situ incorporation of FeNi alloy nanoparticles (FeNi@NCNF) was fabricated via electrospinning, followed by an annealing process. The microstructure observations demonstrate that the FeNi nanoparticles with a size in the range 3–48 nm are homogeneously anchored on a carbon substrate. Benefitting from the advantages of flexible self-supporting of 3D NCNFs and a high electronic conducting FeNi alloy, the optimal FeNi@NCNF electrode exhibited good electrochemical properties with a high reversible charge capacity (406.5 mA h g⁻¹ at 100 mA g⁻¹ after 100 cycles), high coulombic efficiency (coulombic efficiency of 99.9% after 100 cycles), long service life, and superior rate properties (204.6 mA h g⁻¹ at 1 A g⁻¹). These superior electrochemical properties could be attributed to the unique construction of fine FeNi nanoparticles uniformly embedded in NCNFs, which significantly enhanced the utilization factor of the active materials, promoting the transfer of electrons and lithium-ions, and restraining FeNi nanoparticles pulverization/agglomeration during long-term lithiation/delithiation processes. It is reasonable to believe that the flexible self-supporting FeNi@NCNF electrode can be immediately employed in flexible cells without additional additives, which fulfills excellent flexibility and retains good lithium storage properties during physical deformations.