Study On The Synthesis And Electrochenmical Properties Of Ferroferric Oxide Based Composites

Ferroferric oxide is considered as an alternative anode material for lithium ion batteries because of its relatively high theoretical capacity, low cost and environment friendly advantages.The paper mainly studies Fe3O4 anode materials, using differents method to prepare the Fe3O4/graphene nanocomposites.The nanocomposites characterized by X-ray diffraction, Fourier transform infrared spectra, Brunauer-Emmer-Teller surface area measurement, Field emission scanning electron microscope. The electrochemical performance of anode materials for lithium ion batteries was researched by Galvanostatic charge-discharge cycling, cyclic voltammograms and electrochemical impedance spectra.The Fe3O4 were successfully synthesized by a simple precipitation method. The initial discharge capacity of the Fe3O4 electrode is 1381.3 m Ah·g-1 at a current density of 50 m A·g-1.The discharge capacity is 78.5 m Ah·g-1 after 30 cycles. The capacity retention of nanocomposite electrode is 5.68%.The Fe3O4/graphene nanocomposites were successfully prepared by a simple solvothermal method. We studied the influence of the proportion between Fe3O4 and graphene on the morphology and electrochemical performance of nanocomposites.The result shows that Fe3O4 nanoparticles are uniformly wrapped in the graphene sheets.The specific surface area of 77.840 m2·g-1, a total pore volume of 0.370 cm3·g-1 and mesoporous structure existed in the nanocomposite. It was found that the nanocomposite anode with 40.23 wt% graphene has the optimal electrochemical performance in the present study. The initial discharge capacity of the nanocomposite electrode is 1426.9 m Ah·g-1 at a current density of 50 m A·g-1,The discharge capacity is 568.5 m Ah·g-1 after 30 cycles. The capacity retention of nanocomposite electrode is 39.84%.The charge transfer resistance of the nanocomposites is 42.8 ? after 3 cycles at a current density of 50 m A·g-1, which is lower 93.8 ? than that of Fe3O4. The nanocomposite electrode exhibits good cycling stability and excellent electrochemical performance compared to the bare Fe3O4 electrode.The Fe3O4/graphene nanocomposites were successfully prepared by a simple reducing method with hydrazine hydrate as reduction agent. We studied the influence of the suitable dosage of reduction agent and GO on the morphology and electrochemical performance of nanocomposites. It was found that the nanocomposites possess cycle stability by increasing dosage of reduction agent. The nanocomposites possess higher capacity by increasing dosage of GO. It was found that the nanocomposite anode with 28.08 wt% graphene and adding 1.5 ml hydrazine hydrate have the optimal electrochemic- al performance in the present study.At a current density of 50 m A·g-1,the discharge capacity of the nanocomposite anode with 28.08wt% graphene is 489.2 m Ah·g-1 after 30 cycles.The graphene in the composite prepared by reducing method is more thinner and less layers than the graphene in the composite prepared by solvothermal method.The distribution of Fe3O4 in the composite prepared by solvothermal method is more uniform, thus cycle stability is better.