| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 106 === This study was focused on the synthesis and characterization of NVP and NVPF, and found the differences between them. In this study, ascorbic acid and citric acid were used as the mesoporous carbon-coated precursors of NVP and NVPF, respectively. The samples were synthesized by sol-gel method. X-ray diffraction with Topas software for crystal structure refinement, the lattice constant of NVP which a-axis was 8.7336 Å, c-axis was 21.8370 Å; the lattice constant of NVPF which a-axis was 9.0396 Å, c-axis was 10.7544 Å. SEM, TEM help us observe the NVP particle size which was 100-200nm; NVPF was 1-2μm. With the test of BET, the specific surface area of the NVP was 27 m2/g, the diameter of the pores was 4nm, the specific surface area of the NVPF was 18 m2/g, and the diameter of the pores was 4nm, respectively. The Asp3 / Asp2 values were measured with Raman spectroscopy, NVP was 0.26, and NVPF was 0.35. TGA showed that the carbon coating amounts of NVP and NVPF were 6.5 wt% and 6.8 wt%, respectively.
In this experiment, NVP has a single charge / discharge plateau at 3.4V with a specific capacity of 94 mAh/g (theoretical capacity of 117.6 mAh/g). And NVPF had three charge discharge plateaus, (A) 3.35V / 3.41V, (B) 3.67V / 3.71V, (C) 4.22V / 4.15V, the capacity was up to 127.68mAh/g (theoretical capacity of 128 mAh/g). Finally, confirmed that the NVPF have better electrochemical performance.
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