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纳米MnO2超级电容器的研究 总被引:24,自引:0,他引:24
用固相合成法制备纳米MnO2,作为超级电容器材料,通过循环伏安、交流阻抗与恒电流充放电等测试手段对MnO2电极进行分析.结果表明,以1 mol•L-1 KOH为电解液, MnO2电极在-0.1~0.6 V(vs. Hg/HgO)的电压范围内具有良好的法拉第电容性能.在不同电流密度下,电极比容量达240.25到325.21 F•g-1.恒电流充放电5000次后,电极容量衰减不超过10%. 相似文献
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二氧化锰/球形活性炭复合材料在有机系超级电容器中的应用 总被引:2,自引:0,他引:2
以Mn(NO3)2和中间相炭微球基球形活性炭(MSAC)为原料,采用热分解的方法成功制备了一种新型超级电容器用MnO2/MSAC球形复合材料。 通过X射线衍射、扫描电子显微镜和透射电子显微镜对比分析了该复合材料的结构和形貌,并采用循环伏安、恒流充放电、电化学阻抗(EIS)、循环充放电研究了电极的电化学性能。 结果表明,MnO2/MSAC球形复合物中的MnO2粒径为100~160 nm;在1 mol/L的LiPF6/(DMC+EC)(EC:乙烯碳酸酯;DMC:碳酸二甲酯) 有机电解液中MnO2/MSAC复合材料所组装的电容器的工作电压可达3.0 V,在0.002 A/cm2电流密度下,MnO2/MSAC球形复合材料的电容器和单纯MSAC材料的电容器的首次循环比容量分别为186和167 F/g,在循环过程中,MnO2/MSAC球形复合材料的电容器循环200次后充放电的库仑效率基本保持在95%以上。 此外,MnO2/MSAC球形复合材料的充放电曲线表现出典型的电容行为;循环伏安曲线也表现出良好矩型特征,同时具有较高的能量密度和良好的功率性能。 相似文献
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低热固相法制备纳米MnO2/CNT超电容复合电极的循环稳定性 总被引:1,自引:0,他引:1
为了改善纳米MnO2超级电容器电极的充放电循环稳定性,以Mn(OAc)2·4H2O、NH4HCO3和碳纳米管(CNT)为原料,采用低热固相反应得到前驱体,再经焙烧和酸处理,制备了一系列CNT含量不同的纳米MnO2/CNT复合电极材料,并用X射线衍射(XRD)、透射电镜(TEM)和Brunauer-Emmett-Teller(BET)比表面积测定方法对其进行了表征.XRD分析结果表明,复合材料中的MnO2为纳米γ-MnO2.研究了复合电极在1 mol·L-1 LiOH电解质中的电化学性能,并与不含CNT的纯纳米MnO2电极进行了比较.结果表明,含CNTs为10%(w,质最分数,下同)和20%的MnO2/CNT复合电极的循环稳定性远优于纯纳米MnO2电极的循环稳定性,其中含10%CNTs的MnO2/CNT复合电极不仪具有良好的循环稳定性,而且在1000 mA·g-1高倍率充放电条件下仍具有200 F·g-1的高比电容. 相似文献
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碳化物骨架碳是近年来开发的一种具有纳米结构的新型多孔碳材料。由于该材料比表面积大、孔径大小可调、表面化学结构稳定以及成本较低等优点,被认为是超级电容器的理想电极材料之一。骨架碳材料与金属氧化物的复合,或者与导电聚合物的复合,能够将双电层电容与法拉第电容结合,既可提高超级电容器的比电容,改变其充放电电压,又可以提高其循环... 相似文献
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高比能超级电容器的研究进展 总被引:1,自引:0,他引:1
与传统蓄电池相比,超级电容器具有高功率密度、长循环寿命和使用温度范围宽等优势,但其能量密度较低.本文对超级电容器的结构、分类以及发展状况进行了简要介绍,重点阐述了本实验室近年来在研制高性能超级电容器方面的相关工作.主要从两个方面来提高超级电容器的能量密度:(1)通过采用中性水系电解液、有机电解液和离子液体提高对称型碳基超级电容器的电压窗口;(2)应用非对称型超级电容器,即一个电极采用具有法拉第赝电容电极材料或电池电极材料,而另一个电极则采用具有双电层电容的电极材料.同时介绍了由锂离子电池电极材料/活性炭作为正极,石墨作为负极组成的锂离子混合型超级电容器.最后,对超级电容器的发展方向进行了展望. 相似文献
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熔盐处理MnO_2及其超级电容性能研究 总被引:1,自引:0,他引:1
以KCl-NaCl-LiCl熔盐体系处理由固相法制备的MnO2,经XRD、循环伏安、恒流充放电和交流阻抗测试表明,合成的MnO2样品含α-MnO2与γ-MnO2混合晶相,熔盐处理后其结晶程度增加,而且超级电容性能明显提高,放电比容量(129.07 F.g-1)比处理前的(100.94 F.g-1)提高了27.88%.熔盐处理后的样品循环性能良好,充放电效率接近100%,等效串联电阻(RESR)和电极电阻(RE)分别为0.28Ω和0.54Ω. 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献