Preparation And Evaluation Of Electrochemical Performance Of Fe₃O₄Anode Materials Modified With Carbon Source

In recent years，rechargeable lithium-ion batteries （LIBs） have been considered as themost promising energy storage system for a wide variety of applications. Due to the Time’sdemand, they are important power sources for future electric vehicles, hybrid electricvehicles, and emerging smart grids. Rechargeable LIBs offer energy densities2-3times andpower densities5-6times higher than Ni–MH, Ni–Cd, and Pb acid batteries. RechargeableLIBs have many other advantages such as long cycle life, low self-discharge, high operatingvoltage, wide temperature window, and no ‘‘memory effect’’, LIBs is one of the promisingchemical powers.The paper mainly studies Fe₃O₄-based anode materials, focusing on the preparation ofmaterial, specific capacity, cycle efficiency and other important performance. Through theadvanced scientific technology such as X-ray diffraction （XRD）, Scanning ElectronMicroscope （SEM）, Raman, infrared and electrochemical performance test, the crystalstructure, particle size and morphology of samples were studied. Specific capacity ofFe₃O₄-based anode materials is two to three times for carbon-based anode materials, but theattenuation is too fast, carbon materials have good electrochemical stability. Throughcarbon-based anode materials modification Fe₃O₄-based anode materials, the Fe₃O₄/Ccomposite materials possess excellent electrochemical properties.Results of the present study:（1） Through the water bath method for Fe₃O₄/RGO composite, the Fe₃O₄/RGOcomposite exhibits a capacity of367.4mAh/g after50cycles at0.2C and the keeping rate ofcapacity is76.0%. By increasing dosage of reduction agent and adjusting the proportion ofFe₃O₄and GO, Fe₃O₄/RGO composite has a high capacticy of647.3mAh/g after50cycles at0.2C. （2） Through the solvothermal synthesis for Fe₃O₄/graphese composite material, whenthe oxidation graphite is0.3g,8h heating time has good electrochemical performance. In0.2C, the discharge capacity is645.8mAh/g after50cycles, the keeping rate of capacity is87.2%. After50cycles at every0.5C,1C and2C rates, the discharge capacity still keep523.4mAh/g, fully embodies the electrochemical stability of composite materials. Whenheating time is24h, with the addition of more GO, the electrochemical properties is good, in0.2C, the discharge capacity is610.7mAh/g after50cycles, the keeping rate of capacity isas high as93.5%.（3） Through the solvothermal reaction for Fe₃O₄/PGO composite material, the transitionmetal/graphite oxide nanocomposite has both the characteristics of transition metal and thecharacteristics of pyrolysis oxidation graphite, and possesses high conductivity. Fe₃O₄/PGOcomposite can buffer volume change when Li+intercalation/deintercalation compared toFe₃O₄. At0.2C, the discharge capacity is1035mAh/g after50cycles, the dischargecapacity increases upon cycling and has no attenuation. After the high rate （0.2C-0.5C-1C-2C-10C）90times recharge cycles, the discharge capacity for788mAh/g, shows goodelectrochemical circulation performance.