Papers by Author: Yi Jie Gu

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Authors: Hong Quan Liu, Fei Xiang Hao, Feng Lin Yao, Yi Jie Gu, Yun Bo Chen
Abstract: LiFePO4 compound has been paid considerable attention as a promising positive electrode material. In this work, LiFePO4 compound was synthesized by the solid carbon thermal reduction reactions,where Fe2O3, Fe(OH)3 and FeSO4 is used as the iron resource respectively. All the synthesized products are pure phases except that using FeSO4 as the iron resource. The SEM images show porous morphologies, but different iron resource samples show different degree of pore ratio. According to the results of charge/discharge curves, capacity of the sample prepared by Fe(OH)3 as the iron resource shows superior to those of other samples. The result is attributed to more pores in the sample, which is benefit to electrolyte penetrating, short Li-ion diffusion distance.
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Authors: Hong Quan Liu, Fei Xiang Hao, Yi Jie Gu, Yun Bo Chen
Abstract: LiFePO4 has been considered as the most promising positive electrode due to its low cost, high theoretical capacity, stability and low toxicity, all highly required in vehicle applications. In this work, LiFePO4 compound was synthesized by the solid carbothermic reduction reactions with different Li resource. The pure LiFePO4 phase was confirmed for all samples by analysis of the XRD results. The different morphologies were obtained due to different Li resources. The potential plateau of all samples is in the range from 3V to 4V. The sample (LiCO3 as the Li resource) has a higher discharge capacity of 118mAhg−1 at 0.2C 20% greater than that of the sample (LiOH as the Li resource). The reason comes maybe from nano pore characteristics, which reduce Li ion diffusion distance, and increase the utilization efficiency of material.
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Authors: Yan Min Wang, Hui Min Li, Ting Xi Li, Yi Jie Gu
Abstract: Polyaniline nanorods were synthesized via soap-free emulsion polymerization using itaconic acid as dopant and characterized by particle size and distribution measurement, scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA). The particle size of the prepared polyaniline has nearly mono-dispersed property because almost all the particle sizes distribute among the range of 14~110μm. Its morphology consists of the nanorods with the diameter of 50~100nm and the length of 0.1~1μm. FT-IR spectrum indicated that polyaniline of half oxidation state was successfully synthesized and obviously doped with itaconic acid. Moreover, the polymer possesses excellent thermal stability with little weight loss up to 208°C.
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Authors: Yan Min Wang, Hui Min Li, Ting Xi Li, Yi Jie Gu
Abstract: In this paper, polyaniline was successfully synthesized by soap-free emulsion polymerization with glycolic acid ethoxylate lauryl ether as dopant and characterized by particle size and distribution measurement, electron microprobe, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The particle size and distribution measurement indicated that the doped polyaniline is monodisperse and micro-structured. Electron microprobe results showed that its morphology is square slice with different square area and almost the same thickness of about 0.5μm. XRD result illustrated that the polymer possess high crystallinity of 31.43%. FT-IR spectrum revealed the chemical structure of the polyaniline doped with glycolic acid ethoxylate lauryl ether. TGA result showed its good thermal stability and purity.
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Authors: Yi Jie Gu, Yong Hu, Hong Quan Liu, Heng Hui Zhou, Zhen Guo, Zu Wang Hu
Abstract: Spherical Ni0.5Mn0.5CO3 is synthesized via carbonate co-precipitation method which uses NH4HCO3 as the precipitator. However, obvious agglomerate of secondary particles occurs when NH4HCO3 is used as the precipitator. The agglomerate particles can result in inferior physical characteristic. An improved carbonate co-precipitation which used NH4HCO3 doped with different proportion of NaOH as a new precipitator is tested in our study. Observed by SEM and Mastersizer, spherical morphology with narrow particle size distribution is synthesized with the proportion of NaOH reaches 10%. The element line analysis by Electron Probe Micro-analyzer shows symmetrical distributions of Ni and Mn elements via the improved carbonate co-precipitation.
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Authors: Yi Jie Gu, Qing Gang Zhang, Yun Bo Chen, Hong Quan Liu, Yan Min Wang, Fei Xiang Hao, Peng Liu, Shu Qi Li
Abstract: The thermodynamic analysis of Ni2+-Mn2+-NH3-OH--H2O in co-precipitation system was carried out, and the precursor Ni1/2Mn1/2(OH)2 was prepared by hydroxide co-precipitation method. The analysis showed that the best pH value of mixed solution is 11 and the ammonia concentration is 0.4 mol/L, when NaOH is precipitating agent and ammonia is chelating agent. When the pH value is 11, the SEM images confirm that the morphology of Ni1/2Mn1/2(OH)2 is the best.
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