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本文制备了二氧化锰和聚苯胺碳的复合电级材料(MnO2-PAnC),测试结果表明MnO2-PAnC材料为松散结构组成的纳米颗粒. MnO2-PAnC 材料的比电容最大可达459 F•g-1,MnO2-PAnC电极在较高的扫速下循环伏安曲线变形较小,表现出良好的可逆性. 交流阻抗测试结果表明,MnO2-PAnC 电极电荷传递电阻小,表面离子扩散速度快. 充放电500个循环后,MnO2-PAnC 电容的保持率仍高于60%. 以上实验结果表明,MnO2-PAnC 是很好的超级电容器的电极材料. 相似文献
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通过三聚氰胺甲醛树脂(MR)中的羟基与石墨烯氧化物(GO)中的羧基发生的沉淀反应来制备功能化的氧化石墨烯前驱体,然后利用溶胶-凝胶及高温热处理方法制备磷酸钒锂/石墨烯复合材料,利用此材料制备了电池电极,并对电极材料进行了结构和电化学表征。结果表明,所得磷酸钒锂为单斜晶系结构,石墨烯堆叠程度显著降低,也有效避免了磷酸钒锂颗粒的团聚,提高了材料的电化学性能。电池的充放电曲线极化较小,在3.0~4.3 V的区间内20 C倍率仍有86 mA·h/g的可逆容量。0.1 C循环100次后容量为119.7 mA·h/g,容量保持率94%。在3.0~4.8 V的高电压区间,10 C倍率下可逆容量80 mA·h/g,0.1 C循环100次后仍有145.6 mA·h/g的可逆容量。优异的循环和倍率性能以及较低的碳含量符合锂离子正极材料实用的要求。 相似文献
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用恒电位沉积法在2304双相不锈钢基板上制备了纳米结构MnO2薄膜. 用X射线衍射(XRD)、扫描电子显微镜(SEM)以及X射线能量色散谱(EDS)表征了MnO2薄膜的结构、表面形貌和成分. 用循环伏安(CV)、恒流充放电和电化学阻抗谱(EIS)对MnO2电化学性能进行测试和分析. 结果表明, 沉积得到了由100-200 nm纳米棒组成的无定形MnO2薄膜. 随着MnO2质量的增加, 其绝对电容增加, 而比电容逐渐下降; 随着循环伏安扫描速率的增加, 其比电容也逐渐下降. 当MnO2的质量为0.09 mg, 扫描速率为20 mV·s-1时, 比电容达到最大值288.9 F·g-1. 在100 mV·s-1的扫描速率下进行500次CV循环, 其比电容维持在一个稳定值, 且随着循环次数的增加, 比电容略有提高. 相似文献
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超级电容器寿命长,安全性高,并可以实现快速充放电,是化学电源研究的热点之一。然而,超级电容器的能量密度较低限制了其更多的应用。因此,超级电容器领域的研究关注点在如何提高超级电容器的能量密度。其中,提高比容量是提高能量密度的一种有效途径。本文通过对电极材料和电解液的优化来研究制备得到高容量超级电容器的方法。电极材料的比表面积、孔道结构和导电性对其电化学性能有着直接的影响。一方面,通过优化电极材料的孔道结构和比表面积可以增加活性位点并提高电解液离子传导率,从而得到高比电容。另一方面,电极材料导电性的提高有利于提升其电子传导率从而得到较高的比容量。本文分别对碳材料和金属氧化物/氢氧化物的优化达到了增加双电层电容和赝电容的目的。不仅如此,还可以通过在电解液中增加氧化还原电对从而得到高比电容。这一方法为高容量超级电容器的制备提供了新的思路。 相似文献
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通过超声浸渍法以不同浓度的Y(NO3)3溶液成功地制得几种声化学改性锌粉, 以期改善碱性电池锌电极的电化学性能. 利用扫描电镜(SEM)、X射线衍射(XRD)及电化学测试等方法考察了改性锌粉上Y(OH)3/Y2O3的形成及相应锌电极的耐腐蚀和循环性能. 结果表明, Y(NO3)3浓度为0.036 mol·L-1时, 声化学改性锌粉表面均匀分布着颗粒状的Y(OH)3/Y2O3, 且这些钇化合物优先生长在锌粉表面的缺陷位置, 阻挡了电化学过程中锌酸根离子向碱性电解液中的溶解与扩散, 使得相应锌电极的缓蚀效率达79.6%, 且20次循环伏安曲线的阴、阳极峰电位差比空白样减小了285 mV. 将这种改性锌粉和空白锌粉组装成模拟锌银电池, 在250 mA·cm-2的高放电电流密度下测试发现, 声化学改性锌粉的锌电极从1次到30次循环的放电容量损失仅为62.7 mAh·g-1; 且放电容量在50周期时达到322.6 mAh·g-1, 说明声化学改性锌粉可明显提高电极的放电容量和循环寿命. 相似文献
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Kenny Ståhl Tonci Balic-Zunic K. Michael Eriksen Rasmus Fehrmann 《Journal of solid state chemistry》2005,178(5):1697-1704
The crystal structures of K2S2O7, KNaS2O7 and Na2S2O7 have been solved and/or refined from X-ray synchrotron powder diffraction data and conventional single-crystal data. K2S2O7: From powder diffraction data, monoclinic C2/c, Z=4, a=12.3653(2), b=7.3122(1), , β=93.0792(7)°, RBragg=0.096. KNaS2O7: From powder diffraction data; triclinic , Z=2, a=5.90476(9), b=7.2008(1), , α=101.7074(9), β=90.6960(7), γ=94.2403(9)°, RBragg=0.075. Na2S2O7: From single-crystal data; triclinic , Z=2, a=6.7702(9), b=6.7975(10), , α=116.779(2), β=96.089(3), γ=84.000(3)°, RF=0.033. The disulphate anions are essentially eclipsed. All three structures can be described as dichromate-like, where the alkali cations coordinate oxygens of the isolated disulphate groups in three-dimensional networks. The K-O and Na-O coordinations were determined from electron density topology and coordination geometry. The three structures have a cation-disulphate chain in common. In K2S2O7 and Na2S2O7 the neighbouring chains are antiparallel, while in KNaS2O7 the chains are parallel. The differences between the K2S2O7 and Na2S2O7 structures, with double-, respectively single-sided chain connections and straight, respectively, corrugated structural layers can be understood in terms of the differences in size and coordinating ability of the cations. 相似文献
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Xianjin Yang Wenjiao Yuan Xueyan Yang Quanshen Shen 《Journal of fluorine chemistry》2007,128(5):540-544
The free radical additions of fluorine-containing halides to 4-pentenamides initiated by Na2S2O4 were investigated. Both polyfluoroalkyl iodide and ethyl iododifluoroacetate, gave rise to fluorine-containing γ-butyrolactones as the main products while bromides such as ethyl bromodifluoroacetate gave the addition-reduction product. After steric and stereo effects on reaction yields were studied using various substrates, it was concluded that the reactions of 4-pentenamides and polyfluoroalkyl iodides provide one alternative approach to prepare γ-butyrolactones with fluorinated side chains. 相似文献
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通过两步水热法制备泡沫镍(NF)负载Fe_2O_3纳米粒子@Ni_3S_2纳米线网状结构电极(Fe_2O_3@Ni_3S_2/NF)。运用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、N_2吸附-脱附测试等方法对电极材料的物相和微观结构特征等进行了表征。水热条件下原位表面化学刻蚀生成的Ni_3S_2纳米线与三维多孔NF基体间拥有强结合力和低界面电阻,Fe_2O_3粒子均匀分布在纳米线的表面。在1 mol·L~(-1)的KOH溶液中,运用线性扫描伏安测试(LSV)、计时电位法、电化学交流阻抗测试(EIS)等对电极的电催化析氧(OER)性能进行了测试。结果表明:在100 mA·cm~(-2)的超高电流密度下,Fe_2O_3@Ni_3S_2/NF电极的OER过电势仅为223 mV,比Ni_3S_2/NF材料的过电势降低了285 mV;经过10 h计时电位测试,性能保持率高达80%。 相似文献
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The structures of NaRu2O4 and Na2.7Ru4O9 are refined using neutron diffraction. NaRu2O4 is a stoichiometric compound consisting of double chains of edge sharing RuO6 octahedra. Na2.7Ru4O9 is a non-stoichiometric compound with partial occupancy of the Na sublattice. The structure is a mixture of single, double and triple chains of edge-shared RuO6 octahedra. NaRu2O4 displays temperature independent paramagnetism with . Na2.7Ru4O9 is paramagnetic, χ0= with and a Curie constant of 0.0119 emu/mol Oe K. Specific heat measurements reveal a small upturn at low temperatures, similar to the upturn observed in La4Ru6O19. The electronic contribution to the specific heat (γ) for Na2.7Ru4O9 was determined to be15 mJ/moleRu K2. 相似文献
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Hamdi Ben Yahia Etienne Gaudin Cédric Feral-Martin Jacques Darriet 《Journal of solid state chemistry》2010,183(4):776-783
The NaCdVO4-Cd3V2O8 and CdO-V2O5 sections of the ternary system Na2O-CdO-V2O5 have been studied and the crystal structures of Cd3V2O8 and Cd18V8O38 compounds were determined from single-crystal X-ray diffraction data. Cd3V2O8 crystallizes with the maricite-type structure in space group Pnma, a=9.8133(10) Å, b=6.9882(10) Å, c=5.3251(10) Å and Z=4, whereas Cd18V8O38 crystallizes in space group P1 with a new-type structure, a=8.5761(14), b=8.607(3), c=12.896(2) Å, α=95.64(1), β=102.45(1), γ=108.42(1)° and Z=1. The Cd3V2O8 structure is made up of Cd1O4 infinite chains of edge-sharing Cd1O6 octahedra which are parallel to the b direction. The Cd1O4 chains are linked together by VO4 tetrahedra and strongly distorted Cd2O4 tetrahedra. The structure of Cd18V8O38 is based on an ordered three-dimensional framework of cadmium and vanadium polyhedra that share corners. The distorted CdO6 octahedra, CdO5 trigonal bipyramids and CdO5 square pyramids share corners, edges or faces. 相似文献
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电镀烧结法制备Ti/SnO2-Sb2O4电极的研究 总被引:1,自引:0,他引:1
The Ti/SnO2-Sb2O4 electrode has been prepared by the electroplate-sinter method. The effect of SbCl3 adding amount and sintering temperature on its electrode lifetime and oxygen evolution potential were investigated by means of EDX, SEM and XRD analysis. The results indicated that the electrode appeared the best performance when the SbCl3 adding amounts was 0.2g and the sintering temperature was 550℃. In optimized conditions Ti substrate was entirely covered by SnO2-Sb2O4 and the combinations among them were tight. Due to the use of electroplate method, the electrical conductivity, the oxygen evolution potential and the electrode lifetime were increased, so the elec-tro-catalytic activity and the electrochemical stability of the prepared electrode were found to be superior. 相似文献
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运用改进的溶胶凝胶-原位聚合法制备出了兼具电、磁性能的PANI/ZnFe2O4纳米复合材料,借助TEM、XRD、FTIR、四探针电导率仪和VSM(振动样品磁强计)等技术研究了复合材料的结构及其电磁性能。结果表明,通过该法可以实现ZnFe2O4与PANI的有机复合,制得纳米尺寸的、ZnFe2O4与PANI相间以化学键结合的纳米复合材料;复合材料兼具电、磁性能,其导电率随ZnFe2O4含量增加而降低,饱和磁化强度随之而升高,复合物的矫顽力在所研究的含量范围内均较纯ZnFe2O4大,且随ZnFe2O4含量的增加呈先升高后降低的变化趋势。此外,对ZnFe2O4进行HNO3预处理可以有效改善复合材料的电磁性能。 相似文献
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Qiang Dong Yoshinori Yonesaki Takahiro Takei Nobukazu Kinomura 《Journal of solid state chemistry》2011,184(7):1899-1902
A new pyrochlore-type Na0.32Bi1.68Ti2O6.46(OH)0.44 with the cubic cell of a=10.339(5) Å was prepared by hydrothermal reaction using TiO2 (anatase) and Bi2O3 in NaOH solution. This compound was obtained when the molar ratio of NaOH/TiO2 was above 2 and the reaction temperature was above 240 °C. The TG-curve of as-prepared sample showed a mass loss of 0.8 mass% which was caused by release of OH group. This compound decomposed to a pyrochlore-type compound and a layered-type Na0.5Bi4.5Ti4O15 above 800 °C. The optical band gap of Na0.32Bi1.68Ti2O6.46(OH)0.44 was estimated to be 2.5 eV. 相似文献
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Sb2S3/Bi2S3 doped TiO2 were prepared with the coordination compounds [M(S2CNEt)3] (M=Sb, Bi; S2CNEt=pyrrolidinedithiocarbamate) as precursors via gel-hydrothermal techniques. The doped TiO2 were characterized by XRD, SEM, XPS and UV-vis diffuse reflectance means. The photocatalyst based on doped TiO2 for photodecolorization of 4-nitrophenol (4-NP) was examined. The optimal Bi2S3/Sb2S3 content, pH and different doped techniques have been investigated. Photocatalytic tests reveal that M2S3 doped TiO2 via the gel-hydrothermal route performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP). 相似文献