Preparation Of Electrode Materials For Lithium Ion Batteries From FeOOH And Their Electrochemical Performances

Lithium ion batteries have become the primary choice of the green secondarybatteries in the21th century due to their high energy density, good cyclingperformance, high working voltage and environmental friendliness, etc. In thisdissertation, the preparation and electrochemical properties of LiFePO₄/C cathodematerial and Fe₂O₃anode material have been investigated.LiFePO₄/C cathode material has been synthesized by a carbothermal reductionmethod with self-prepared β-FeOOH nanorods as raw materials, and the influenceof the carbon content on their electrochemical performances of the LiFePO₄/Ccathode materials has been studied. The results indicate that LiFePO₄/C cathodematerial with carbon content of about2.79wt.%can display an excellentelectrochemical performance. It can deliver discharge capacities of158.8,153.2,144.3,126.8,111.0and92.9mAh g^-1at0.1,0.5,1,5,10and15C, respectively.And with decreasing the current density from15C back to0.1C, the dischargecapacity has been returned to157.5mAh g^-1, which is99.2%of the initial capacity.Fe₂O₃anode material has been synthesized by a sintering method in air withself-prepared β-FeOOH nanorods as raw material. Its electrochemical performanceshave been investigated. Fe₂O₃anode material delivers a high discharge capacity of1667.0mAh g^-1in the first cycle,1161.0mAh g^-1in the second cycle （70%of theinitial discharge capacity）, and can retain459.7mAh g^-1after50cycles at a currentdensity of50mA g^-1.At last, the electrochemical performance of a complete lithium ion batteryconstructed of LiFePO₄/C cathode and Fe₂O₃anode has been investigated. Thecomplete lithium ion battery delivers an initial discharge capacity of148.7and441.7mAh g^-1at0.1C based on LiFePO₄and Fe₂O₃, respectively. The dischargecapacities of the complete lithium ion battery have no degradation at differentdischarge rates after4cycles, and back to0.1C, the discharge capacity has noobvious degradation compared to the average initial discharge capacities at0.1C. Itshows excellent cycling performance.