Long-cycle performance of the hollow and sandwich structured of H-TiO2/Fe3O4/C anode material for lithium-ion batteries

Abstract

First, a spherical Fe₃O₄ was synthesized using the hydrothermal method, and subsequently coated with carbon to form a core–shell C/Fe₃O₄ composite. The Fe₃O₄ core was then dissolved in an etching solution to create a hollow carbon (H-C) structure. This H-C served as a substrate onto which a Fe₃O₄ layer was deposited via the hydrothermal method, resulting in a hollow core–shell Fe₃O₄/C composite. Finally, the solvothermal method was employed to coat the Fe₃O₄/C composite with a layer of hydrogenated titanium dioxide (H-TiO₂), resulting in a hollow-structured H-TiO₂/Fe₃O₄/C material. This structure not only ensures the formation of a dual-core shell structure, but also reduces the proportion of carbon material in the composite electrode, thereby enhancing the theoretical specific capacity of the composite electrode. The presence of H-TiO₂ and carbon improved the cyclic stability of Fe₃O₄ within the composite. This hollow sandwich–structured composite demonstrated excellent electrochemical performance, delivering a discharge specific capacity of 629.5 mAh g⁻¹ after 500 cycles at 0.2 A g⁻¹, along with a high initial coulombic efficiency of 80.6%.