Abstract:

As a lithium-ion battery anode material, the Fe₃O₄ exhibits varying volume during charging and discharging, which results in serious capacity degradation. This problem can be solved using carbon coating. Thus, in this paper, three-dimensional graphene-coated Fe₃O₄ nanoparticle(3DG@Fe₃O₄) composites were synthesized by one-step hydrothermal method using graphene oxide (GO) and Fe²⁺ as raw materials. The composites were characterized by a Fourier transform infrared spectrometer, thermal gravimetric analyzer, X-ray diffractometer, Raman spectrometer and scanning electron microscopy. The results showed that the composites have a "sandwich" structure of graphene (G)-coated Fe₃O₄ nanoparticles. Meanwhile, electrochemical tests, including galvanostatic cycling with potential limitation, cyclic voltammetry, and alternating current impedance were used to investigate the influence of Fe₃O₄ content on the lithium-ion storage performance of 3DG@Fe₃O₄ composites. The 3DG@Fe₃O{}_{\mathrm{4}}^{}-2 electrode with about 83.2% Fe₃O₄ exhibited enhanced specific capacity and better cycle stability. It also delivered a high discharge specific capacity of 1412.33 mAh/g at a current density of 0.1 A/g and 577 mAh/g after 100 cycles, and this value was 6.5 times that of pure Fe₃O₄ electrode material after 100 cycles. The composites prepared by this method have simple synthesis and do not require additional reducing agent. The prepared composites have high capacity and good cycle stability compared with pure Fe₃O₄ nanoparticles, and this can promote the application of Fe₃O₄-based anode materials in the field of energy storage.

Key words: hydrothermal process, carbon coating, Fe₃O₄, lithium-ion battery, anode material