Flexible Fe ₃ O ₄ nanoparticles/N-doped carbon nanofibers hybrid film as binder-free anode materials for lithium-ion batteries

The energy and power density of lithium-ion batteries (LIBs) can be effectively improved by designing flexible free-standing electrodes. Here, a flexible film composed of Fe ₃ O ₄ nanoparticles (NPs) embedded in N-doped carbon nanofibers (Fe ₃ O ₄ /NCNFs) was prepared through electrospinning and subsequent annealing process. The Fe ₃ O ₄ /NCNFs film can be directly used as anode materials for LIBs without conductive additive, current collector, and binder. Electrochemical measurement results indicate that the Fe ₃ O ₄ /NCNFs electrode exhibits excellent cycling stability and retains the capacity of 522 mAh g ⁻¹ after 200 cycles at 0.1 A g ⁻¹ . Furthermore, the Fe ₃ O ₄ /NCNFs electrode also shows good rate performance and still obtains a specific capacity of 407 mAh g ⁻¹ even at 5 A g ⁻¹ . The superior electrochemical performance should be attributed to the flexible self-standing characteristic of the electrode and the synergistic effects between 3D conductive NCNFs and Fe ₃ O ₄ NPs.