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以三聚氰胺为氮源,通过固相法成功合成了掺氮碳包覆的磷酸铁锂10%-NC-LFP。通过扫描电子显微镜和激光颗粒粒度分析来检测材料的微观形貌和宏观颗粒。颗粒表面氮掺杂的碳层可以提高LiFePO_4的电子电导率,与未掺杂的碳(C-LFP)相比,容量更高,倍率性能更好。实验表明,10%-NC-LFP的放电比容量在0.2C时为166mAh/g,在10C时为134mAh/g;C-LFP在0.2C时为164mAh/g,10C时为120mAh/g。本研究方法在提高LiFePO_4导电性方面非常有效,可应用于其他正极材料的合成。 相似文献
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采用水热法、化学沉积法、有机溶剂还原法,逐步合成了择优生长、石墨烯基复合材料包覆改性的锂离子电池四元复合正极材料LiFePO_4/CuO/Ag/RGO。分别采用XRD、TEM和循环充放电等手段对材料进行性能表征。结果表明,包覆后的LiFePO_4呈橄榄石型结构,包覆材料未对LiFePO_4结构和晶型产生影响。所制备的材料呈现择优生长的棒状结构,石墨烯基复合材料将LiFePO_4包覆,构成稳定的导电网络。电化学性能测试表明,改性后的复合材料在0.2C倍率下首次充放电比容量最高达到166mA·h/g。即使在50C高倍率下首次放电比容量依然达到87.9mA·h/g,表现出优良的的倍率和循环稳定性。 相似文献
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为了研究非金属元素包覆和金属元素掺杂对LiFePO_4的电化学性能和振实密度的影响,用固相反应法制备了炭包覆的LiFePO_4/C和铜掺杂的LiFe_(0.95)Cu_(0.05)PO_4正极材料,并对所制材料进行了XRD、SEM、充放电循环、倍率性能和振实密度的测试.结果显示:LiFePO_4/C和LiFe_(0.95)Cu_(0.05)PO_4的循环平均容量分别达到147mAh/g和131mAh/g;在高倍率放电时,LiFe_(0.95)Cu_(0.05)PO_4的容量衰减远大于LiFePO_4/C.LiFePO_4/C材料的各项电化学性能都优于LiFe_(0.95)Cu_(0.05)PO_4材料,而LiFe_(0.95)Cu_(0.05)PO_4材料的振实密度远大于LiFePO_4/C材料的振实密度,前者是后者的1.5倍. 相似文献
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以往的研究证实,采用PAM模板合成法合成的LiFePO4/C复合材料,具有颗粒尺寸小,倍率放电性能好,电化学比容量较高等特点[1].本文在此基础上对复合材料进行体相掺杂高价金属离子,所得掺杂基LiFe0.99M0.01PO4/C(M=Nd3+、Co3+、Cr3+、Mn3+)改性材料的比容量有了进一步提高.研究结果表明,C/3充放电时,复合LiFePO4/C的容量为108mAh·g-1,而掺杂基LiFe0.99M0.01PO4/C的比容量分别提高到140、129、120和115mAh·G-1,而且循环性能也非常稳定.电导率研究表明,体相掺杂使得体相电导率提高了5到7个数量级,与文献值较为接近.XRD衍射图谱表明,掺杂后各个材料的结构依然保持有序的橄榄石结构. 相似文献
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在溶液中制备FePO_4·2H_2O前驱体,利用氢气还原法于650℃制得了锂离子电池正极材料LiFePO_4,并对其进行了包覆和掺杂.采用X射线衍射法(XRD)、扫描电镜法(SEM)、循环伏安法(C-V)、交流阻抗法(EIS)及充放电测试对材料进行了结构表征和电化学性能测试.结果表明,该方法制得的材料具有单一的橄榄石结构,样品形貌规则、颗粒均匀.包覆碳和掺镁后,材料具有较低的阻抗及较高的首次放电比容量,LiFePO_4、LiFePO_4/C、LiMg_(0.01)Fe_(0.99)PO_4/C的首次放电比容量分别为125.09mA·h/g、139.17mA·h/g、146.97mA·h/g. 相似文献
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采用乙二醇溶剂热法,以蔗糖为碳源,制备了橄榄石型纳米级LiFePO4/C复合正极材料,对其物相、形貌、结构、成分和性能进行了表征。结果表明,所制备的纳米LiFePO4/C的形貌为棒状,直径约为100 nm,结晶度高、分散性好。LiFePO4的粒径细化和掺碳有利于提高LiFePO4正极材料的电化学性能,其首次充放电比容量(0.1 C)分别为166 mAh·g-1和164 mAh·g-1,充放电电压平台分别为3.45 V和3.40 V;在5 C大倍率放电下,经过20次循环,其比容量保持率为95.4%。 相似文献
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Andréia Soares Zola Renata Uema Ribeiro José Maria Correa Bueno Daniela Zanchet 《Journal of Experimental Nanoscience》2014,9(4):398-405
This work aimed to study cobalt nanoparticles (Co-NPs) preparation using three different methods in order to evaluate the effect of synthesis variables that can influence the nanoparticle size distribution and particle shape. The synthesised nanoparticles were characterised by Transmission Electron Microscopy. The first synthesis employed decomposition of Co2(CO)8, at high temperatures. This procedure resulted in spherical nanoparticles with low size distribution. The size of Co-NPs could be tuned by modification of precursor/surfactant, nevertheless the stirring and injection time influenced the size distribution. Using polyol process, at high temperatures, it was produced undefined-shape nanoparticles. This result suggests that the solution composition, i.e. the amount of trioctylphosphine and oleic acid was not suitable to control both size and shape of nanoparticles. Finally, the method based on reduction with NaBH4 resulted spherical nanoparticles with tiny sizes, indicating that in this case a variation on amount of reductant would be more efficient on the particle size control than a variation in concentration of oleic acid. These results indicated that, for each method, a different variable exists for the control of the distribution size and the shape of the formed particles. 相似文献
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镁离子掺杂对磷酸铁锂结构和性能的影响 总被引:3,自引:0,他引:3
为提高LiFePO4的充放电性能,用化学沉淀法制备了镁离子掺杂的磷酸铁锂,用电化学方法测量了Li1-xMgxFePO4(x=0.00、0.02、0.05、0.07、0.10和0.20,摩尔分数)的充放电性能,用X射线衍射(XRD)和里特沃尔特(Rietveld)方法表征了掺杂对LiFePO4的晶体结构的影响.结果表明少量镁离子掺杂能有效地提高LiFePO4的比容量和循环性能,其中Li0.95Mg0.05FePO4具有更好的电化学性能,放电比容量高出LiFePO4约20mAh/g,镁离子掺杂提高了LiFePO4中Fe3 /Fe2 共存态的浓度,使材料具有更好的导电能力. 相似文献
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采用葡萄糖、环氧树脂、酚醛树脂为碳源制备了LiFePO4/C复合材料。利用X射线衍射、扫描电镜等方法对复合材料进行研究。结果表明,葡萄糖获得了碳包覆复合材料,而环氧树脂、酚醛树脂则得到了碳芯结构复合材料。碳芯结构复合材料的电化学性能优于碳包覆复合材料,电流密度为15mA/g时,试样C、D的放电容量分别为165、167mAh/g;电流密度为600mA/g时,试样C、D的放电容量分别为139.4、145.5mAh/g,经过50循环后容量保持率分别高达99.2%、99.5%。 相似文献
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Prakash ThangarajJayaprakash Rajan Sathyaraj DuraiSanjay Kumar Ayalsomayajula RatnaPhaniGiovanni Neri 《Vacuum》2011,86(2):140-143
The size controlled zinc oxide nanoparticle is synthesized in the isothermal evaporation method with albumen (egg white). This method is simple and cost effective for synthesis of ZnO nano powder. The egg white foam was assisted to increase the reaction rate and produce the zinc oxide nano powder. This method helps to attain the particle size in the range 13-28 nm. The results from X-ray diffraction patterns and TEM micrograph confirmed the formation of nano crystalline phase with particle size ranges from 13 nm to 28 nm. The samples were further analyzed by using Fourier transform Infrared spectroscopy (FT-IR), photoluminescence spectrum (PL), thermogravimetric analysis (TGA) and Resistivity measurement. The less time consumption in isothermal evaporation process was one of the significant roles for large scale zinc oxide nano powder production. 相似文献
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《Vacuum》2012,86(2):140-143
The size controlled zinc oxide nanoparticle is synthesized in the isothermal evaporation method with albumen (egg white). This method is simple and cost effective for synthesis of ZnO nano powder. The egg white foam was assisted to increase the reaction rate and produce the zinc oxide nano powder. This method helps to attain the particle size in the range 13–28 nm. The results from X-ray diffraction patterns and TEM micrograph confirmed the formation of nano crystalline phase with particle size ranges from 13 nm to 28 nm. The samples were further analyzed by using Fourier transform Infrared spectroscopy (FT-IR), photoluminescence spectrum (PL), thermogravimetric analysis (TGA) and Resistivity measurement. The less time consumption in isothermal evaporation process was one of the significant roles for large scale zinc oxide nano powder production. 相似文献