Preparation of fluorine-doped, carbon-encapsulated hollow Fe3O4 spheres as an efficient anode material for Li-ion batteries

Abstract

Herein we report the design and synthesis of fluorine-doped, carbon-encapsulated hollow Fe₃O₄ spheres (h-Fe₃O₄@C/F) through mild heating of polyvinylidene fluoride (PVDF)-coated hollow Fe₃O₄ spheres. The spheres exhibit enhanced cyclic and rate performances. The as-prepared h-Fe₃O₄@C/F shows significantly improved electrochemical performance, with high reversible capacities of over 930 mA h g⁻¹ at a rate of 0.1 C after 70 cycles, 800 mA h g⁻¹ at a rate of 0.5 C after 120 cycles and 620 mA h g⁻¹ at a rate of 1 C after 200 cycles. This improved lithium storage performance is mainly ascribed to the encapsulation of the spheres with fluorine-doped carbon, which not only improves the reaction kinetics and stability of the solid electrolyte interface film but also prevents aggregation and drastic volume change of the Fe₃O₄ particles. These spheres thus represent a promising anode material in lithium-ion battery applications.