Binder-free 3D porous Fe3O4–Fe2P–Fe@C films as high-performance anode materials for lithium-ion batteries

Abstract Slow lithium storage reaction kinetics and huge volume changes are the main limiting factors for the large-scale application of transition metal oxide anode materials for lithium ion batteries. Developing multi-structure and carbon coating films is a promising solution. Herein, a facile strategy for synthesizing novel binder-free 3D porous Fe3O4–Fe2P–Fe@C films is proposed based on the electrodeposition of self-supporting porous FeOOH–FeP–Fe films, glucose coating to form FeOOH–FeP–Fe@Glucose films, and oxygen-free annealing treatment for the decomposition of FeOOH into Fe3O4, phase separation of FeP into Fe2P–Fe3P and pyrolysis of glucose into C. The binder-free Fe3O4–Fe2P–Fe@C film anode exhibits high reversible capacity (914 mA h g−1 after 200 cycles at 0.1 A g−1), superior rate capability (518 mA h g−1 at 5 A g−1), and stable long cycling performance (723 mA h g−1 after 500 cycles at 2 A g−1). The excellent lithium storage performance of the Fe3O4–Fe2P–Fe@C anode is attributed to the synergistic effects of the self-supporting 3D porous film structure, multi-phase structure, and carbon coating, which not only enhances the Li+ and electron transport to accelerate the reaction kinetics, but also buffers the volume changes to improve the structure stability during reversible charge-discharge process.