| Summary: | 碩士 === 明志科技大學 === 化學工程研究所 === 102 === Lithium iron phosphate (LiFePO4, LFP) is a promising alternative cathode material because of its low material cost, environmental friendliness, superior thermal safety, and long operational life. In this study, LFP cathode materials were prepared by solid-state method combined with the wet grinding process to reduce the particle size. Then, the thin carbon film was subsequently coated on the surface of LFP particles by using the spray drying and annealing treatment. The effects of spray drying on the electrochemical properties of lithium iron phosphate/carbon (LFP/C) composites were also investigated.
The prepared LFP/C cathode composites were characterized by XRD, SEM, DLS, BET, Raman and EA analysis. XRD analysis indicates the prepared cathode materials with the olive-type phase have a high crystallinity and no impurity phase is observed. EA analysis shows that the carbon content of LFP/C is in the range of 6-7% that is independent of spray drying operation. Raman analysis illustrates that the operating condition of spray drying has an obvious influence on the extent of carbon graphitization and coverage on the LFP surface. Moreover, the charging/discharging analysis shows that the prepared LFP/C composites exhibit high capacity of 140mAh/g at 0.1C and 69.84mAh/g at 10C, respectively. The results shows that performance of LFP/C composites as the cathode materials can be significantly improved by using the spray drying.
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