共查询到20条相似文献,搜索用时 15 毫秒
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以锂∶铁∶磷摩尔比为1∶1∶1为原料,采用溶剂热法合成了纯的、晶型规则的亚微米级LiFe-PO4;再加入酚醛树脂经高温处理合成了LiFePO4/C复合正极材料,其振实密度高,加工性能好。利用X射线衍射(XRD)、扫描电子显微镜(SEM)及恒电流充放电技术研究了溶剂热温度、时间对产物组织结构及性能的影响。结果表明溶剂热温度为190℃、溶剂热时间为24h合成样品表现出良好的电化学综合性能,振实密度为1.25g/cm3;室温下0.1C倍率充放电,放电比容量达到151.3mAh/g;在1C倍率下放电时,材料放电比容量仍能保持在120.1mAh/g左右。 相似文献
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LiFePO4/C正极材料的液相合成及电化学性能研究 总被引:3,自引:0,他引:3
采用磷酸三丁酯(TBP)为多功能反应物并添加表面活性剂PEG-4000合成了LiFePO4/C正极材料,利用XRD、SEM、XPS和滴定分析对产品进行了结构、表面形貌和化学组成表征.结果表明在650℃烧结15h所得产物结晶良好,为均匀分布在100nm左右的类球形颗粒.循环伏安曲线显示,该样品具有对称且尖锐的氧化还原电位峰,表明材料具有良好的电化学可逆性.在0.1mA/cm2电流密度下,其首次充放电比容量分别为162和158mAh/g,经100次循环后放电容量损失率仅为3.3%,当充放电密度增加到4mA/cm2时,材料的放电比容量仍然接近100mAh/g,倍率性能优良. 相似文献
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《Materials Letters》2007,61(8-9):1667-1670
Bi2S3 nanorods were synthesized via a simple solvothermal process in polyol media through the reaction between Bi(NO3)3·5H2O, urea and CS2 at 150 °C for 15 h using diethylene glycol as solvent. The nanorods were characterized by XRD, TEM and SAED. The results showed that the products were well-crystallized orthorhombic phase with lattice parameters a = 11.15 Å, b = 11.3 Å and c = 3.984 Å, which are consistent with the value in standard JCPDS card No. 17-0320. DEG served as an excellent solvent and structure director. Besides, compared to water and EG as solvents, the DEG system can provide a mild and homogenous condition, which is favorable to anisotropic growth and increases the yield of high quality Bi2S3 nanorods. Based on the experimental results, the growth mechanism was discussed. 相似文献
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M. Alagiri C. Muthamizhchelvan Sharifah Bee Abdul Hamid 《Journal of Materials Science: Materials in Electronics》2013,24(11):4157-4160
The superparamagnetic (SPM) cobalt nanoparticles with an average size of 2 nm have been prepared through a solvothermal process in the presence of triethanolamine. The synthesized nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and superconducting quantum interference device magnetometer. X-ray diffraction analysis confirms the face centered cubic phase of as-prepared cobalt nanoparticles. Transmission electron microscopy was employed to study the morphology of the as-prepared product, which exhibit spherical-like shape with size around 2 nm. The high resolution transmission electron microscopy image of cobalt nanoparticles shows the lattice spacing value of 0.204 nm. This is well matched with the (111) lattice spacing of fcc Co. XPS revealed the prepared product is pure cobalt. The blocking temperature of 17 K was obtained and confirmed by field-cooled and zero-field-cooled plots. The hysteresis loop revealed the synthesized nanoparticles have SPM character at room temperature. 相似文献
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Synthesis of silver nanoparticles using the polyol process and the influence of precursor injection 总被引:1,自引:0,他引:1
Spherical silver nanoparticles with various sizes and standard deviations were synthesized by the polyol process. Two different synthesis methods were compared in order to investigate the influence of reaction parameters on the resulting particle size and its distribution. In the precursor heating method, wherein a solution containing silver nitrate was heated to the reaction temperature, the ramping rate was determined to be a critical parameter affecting the particle size. In contrast, in the precursor injection method, in which a silver nitrate aqueous solution was injected into hot ethylene glycol, because of rapid nucleation, the injection rate and the reaction temperature were important factors in terms of reducing the particle size and attaining monodispersity. Silver nanoparticles with a size of 17 ± 2?nm were obtained at an injection rate of 2.5?ml?s(-1) and a reaction temperature of 100?°C. 相似文献
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In this work, we report on the synthesis of hybrid Au–ZnO nanoparticles using a one-pot chemical method that makes use of 1,3-propanediol as a solvent, a reducing agent and a stabilizing layer. The produced nanoparticles consisted of Au cores decorated with ZnO nanoparticles. The structure and morphology of the nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDX) and Raman spectroscopy. Optical extinction measurements, combined with numerical simulations, showed that the Au–ZnO nanoparticles exhibit a localized surface plasmon resonance (SPR) clearly red-shifted with respect to that of bare Au nanoparticles (AuNPs). This work contributes to the emergence of multi-functional nanomaterials with possible applications in surface plasmon resonance based biosensors, energy-conversion devices, and in water-splitting hydrogen production. 相似文献
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Co3O4 nanoparticles and cobalt (fcc-Co) powders were successfully synthesized by solvothermal process from a single precursor. The reaction of Co(Ac)2 with sodium dodecylbenzenesulfonate (SDBS) shows evident-dependent temperature effect. At 180 °C, Co(Ac)2 reacts with SDBS to produce precursor CoCO3 plate structures, which are assembled by small nanoparticles. At the temperature of 250 °C, the precursor CoCO3 can be gradually decomposed to form Co3O4 nanoparticles with diameter of ca. 70 nm. While, at 250 °C, the reaction of Co(Ac)2 with SDBS also produce precursor CoCO3 nanoparticles/plates, but the CoCO3 nanoparticles/plates would only decompose to give metal Co. In this process, SDBS acts as not only a surfactant but also a reagent. Magnetic measurements reveal that the as-prepared Co3O4 nanoparticles exhibit weak ferromagnetic properties and Co powders show ferromagnetic properties. In addition, a possible formation mechanism was elaborately discussed. 相似文献
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利用碳热还原法合成了Li1-xMgxFePO4/C(x=0.00、0.01、0.02、0.03、0.04、0.05、0.1)正极材料,通过XRD、SEM、BET、CV、EIS和恒流充放电实验研究了不同掺杂量对产物结构和电化学性能的影响。结果表明少量Mg的掺杂未影响到LiFePO4的晶体结构,但显著改善了其电化学性能。其中,Li0.98Mg0.02FePO4/C材料具有更好的电化学性能,0.1C倍率放电时,首次放电容量达到165.2mAh/g,且循环性能良好。另外,对合成材料的红外光谱进行了研究和指认。 相似文献
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《Materials Letters》2006,60(17-18):2105-2109
Two synthesis routes for the production of LiFePO4 particles were investigated in water at subcritical and supercritical conditions. Micron and nano-sized particles of LiFePO4 were obtained via both routes, with nano-sized particles predominating when temperature was above the critical temperature of water. Our results suggest that synthesis in supercritical water is attractive for obtaining nanometer-sized crystalline particles of LiFePO4 with a low degree of agglomeration. Electrochemical tests showed that this material exhibited improved capacity compared with LiFePO4 prepared via other methods. 相似文献
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CoPt nanoparticles with an average size of 3?nm and narrow distribution were synthesized by chemical reduction of Co(CH(3)COO)(2) and Pt(acac)(2) by polyethyleneglycol-200. The as-prepared nanoparticles have a disordered fcc structure which transformed after thermal treatment to an ordered fct structure, which results in coercivity up to 6?kOe at room temperature and 9?kOe at 5?K because of the high magnetocrystalline anisotropy of the tetragonal structure [Formula: see text]. 相似文献
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《Materials Letters》2007,61(4-5):1260-1264
Well-crystallized LiFePO4 was directly synthesized by the KCl molten salt (MS) method. According to this method, the pre-sintered intermediate was mixed with KCl, and then sintered at a certain temperature, which was determined by thermogravimetric analysis (TGA). The olivine structure and spherical morphology were confirmed by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The spherical products show a higher tap density, which will benefit the enhancement of volumetric energy density. The electrochemical behavior was studied by cyclic voltammetry and galvanostatic tests. The LiFePO4 product sintered at 755 °C for 3 h exhibits the best electrochemical performance. At a rate of 0.1 C, it can deliver an initial capacity of 130.3 mAh g− 1, and a capacity of 137.2 mAh g− 1 at the 40th cycle. At a high discharge rate of 5 C, it still exhibits a capacity of 92 mAh g− 1. 相似文献
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R. Justin Joseyphus K. Shinoda Y. Sato K. Tohji B. Jeyadevan 《Journal of Materials Science》2008,43(7):2402-2406
A low temperature synthesis method using a modified polyol process is employed to synthesize FePt nanoparticles even at 393 K.
The composition could be controlled using the above process by varying the reaction conditions to obtain Fe50Pt50 nanoparticles at 473 K. The magnetic properties of the fcc-FePt nanoparticles indicate that they are not completely superparamagnetic
in spite of the smaller particle size. 相似文献
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Dongqun Shao Jinxian Wang Xiangting Dong Wensheng Yu Guixia Liu Feifei Zhang Limin Wang 《Journal of Materials Science: Materials in Electronics》2013,24(11):4263-4269
LiFePO4/C composite nanofibers were synthesized by calcination of the [LiOH + Fe(NO3)3 + H3PO4]/PVP electrospun nanofibers. Polyvinyl pyrrolidone (PVP) was used as the electrospinning template and carbon source. During the calcination [LiOH + Fe(NO3)3 + H3PO4] were transformed to LiFePO4 and PVP was decomposed into carbon. The morphology and properties of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller (BET) specific surface area analysis, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements. The results indicate that the mean diameter of as-prepared LiFePO4/C composite nanofibers is 179.08 ± 29.66 nm and the BET specific surface area is 66.59 m2 g?1. The addition of carbon does not affect the structure of LiFePO4, but improves its electrochemical performances. At the current density of 0.2 C, the initial discharge capacity of LiFePO4/C electrode is 133.6 mAh g?1 and there is no obvious capacity fading after 100 cycles. The formation mechanism of the LiFePO4/C composite nanofibers was also proposed. 相似文献
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PURUSHOTTAM KUMAR SINGH PANKAJ KUMAR MANOWAR HUSSAIN ALOK KUMAR DAS GANESH CHANDRA NAYAK 《Bulletin of Materials Science》2016,39(2):469-478
In the present study, cupric oxide (CuO) nanoparticles were synthesized by electrochemical discharge process using strong base electrolytes. The experiments were carried out separately using NaOH and KOH electrolytes. The mass output rate and the crystal size were obtained with variation of the rotation speed of magnetic stirrer for both types of electrolytes. The mass output rate of CuO nanoparticles increased with the increase in the speed of rotation, and, after an optimum speed, it started decreasing. However, the size of the particles reduced with the increase of the rotation speed. The crystal plane of the obtained CuO nanoparticles was similar for both the electrolytes whereas the yield of nanoparticles was higher in KOH as compared with NaOH under the same experiment conditions. In this set of experiments, the maximum output rates obtained were 21.66 mg h?1 for NaOH and 24.66 mg h?1 for KOH at 200 rpm for a single discharge arrangement. The average crystal size of CuO particles obtained was in the range of 13–18 nm for KOH electrolyte and 15–20 nm for NaOH electrolyte. Scanning electron microscopy images revealed that flower-like and caddice clew-shaped CuO nanocrystalline particles were synthesized by the electrochemical discharge process. Fourier transform infrared spectrum showed that the CuO nanoparticles have a pure and monolithic phase. UV–vis–NIR spectroscopy was used to monitor oxidation course of Cu → CuO and the band gap energy was measured as 2 and 2.6 eV for CuO nanoparticle synthesized in NaOH and KOH solutions, respectively. 相似文献