Synthesis, Carbon-coating And Electrochemical Performance Of Iron-based Oxide Nanomaterials

Fe3O4is one of the conversion-type anode materials, which exhibits high theoretical capacity and comparable conductivity, as well as other advantages, such as natural abundance, low cost and non-toxicity. However, micro/nanosized Fe3O4is prone to suffering from fast capacity fading resulting from the agglomeration and large volume variation during lithium insertion/extraction, which is one of the major obstacles for Fe3O4anodes to be commercialized. The most attractive and effective strategies to enhance the electrochemical performance of Fe3O4anodes are designing Fe3O4with special nanostructures or compositing Fe3O4with carbon.The FeCO3microspheres were synthesized via solvothermal routes using FeCl2·4H2O and Na2CO3as reagents. The formation mechanism and the effects of different solvents on the morphology of FeCO3microspheres were studied by means of XRD, FT-IR, and FESEM. the porous Fe3O4microspheres could be obtained by calcining any kind of FeCO3microspheres at480℃for5h. Fe3O4microspheres exhibit a reversible capacity of770mAh g-1at100mA g-1and151mAh g-1at1600mA g-1.A fast and scalable process was studied using dicyclopentadiene as carbon precursor. Characterization by XRD, HRETM, FESEM, Raman and TGA on the products reveals that this process exhibits higher carbon-coating efficiency than the common used hydrothermal carbonization. The Fe3O4/C obtained via this novel method presents excellent electrochemical performance:592mAh g-1at100mA g-1after55cycles and182mAh g-1at1600mA g-1.Solid-state reaction method was employed to prepared Fe2O3 Y0.02Fe1.98O3, Y0.1Fe1.9O3, La0.02Fe1.98O3, and La0.06Fe1.94O3. The effect of the Y, and La doping on the structure and electrochemical performance of the Fe2O3was studied. The the unit cell volume decreased after rare earth doping. Rare earth doped Fe2O3presented enhanced reversible capacities at the first several cycles. In addition,0.02La doped Fe2O3exhibited enhanced conductivity. The rate performance of La doped Fe2O3is superior to the Fe2O3before doping.