| Summary: | 碩士 === 國立臺北科技大學 === 化學工程研究所 === 99 === This project will improve the disadvantage of conventional hydrothermal method, to prepare LiFePO4 powder by microwave solvothermal. we use microwave to prepare because it has several characteristics: (1) faster reaction rate, (2) milder reaction conditions, (3) higher chemical yield, (4) lower energy consumption, (5) better reaction selectivities.
Experiment, the precursors of LiFePO4 were synthesized by precipitation named one step synthesis and two steps synthesis separately. The source of lithium hydroxide, ferrous sulfate, phosphoric acid as a synthetic raw material. Using ethylene glycol as solvent that used to conduct reaction in the microwave system and studying the relationship between microwave power, time, temperature and synthetic environment of one-step and two-steps synthesis methods separately. We explore the form, the crystalline phases and analysis of lattice defects by SEM, XRD ,TEM and SEM/EDX.
According to the experiments, we found that one-step and two-steps synthesis methods separately in the microwave conditions for the 600W-200W, 180 ℃, N2 system, and the microwave time was 20min and 80min respectively synthesized LiFePO4 cathode material, And then, the conductive polymer is coated LiFePO4 cathode material. Finally, Four-point probe to test its conductivity. We found that PET (high content of poly 3,4-ethylenedioxythiophene, PEDOT) is the best.
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