复合电极中聚苯胺含量对超级电容器电化学性能的影响

采用原位复合法和界面聚合法分别制备了纤维状的聚苯胺/乙炔炭黑复合材料和聚苯胺,讨论了复合电极中聚苯胺含量对超级电容器电化学性能的影响。研究表明,复合电极材料中聚苯胺的含量不是影响其电化学性能的决定性因素。聚苯胺/乙炔炭黑复合电极(直径约200nm)在5mA/cm2和1mol/L的H2SO4溶液中首次充放电单电极比电容高达432F/g,该值比聚苯胺含量高的复合电极和直径相近纯聚苯胺电极的单极比电容值354和416F/g都高。     

柔性聚苯胺电极体积电容的提高:溶液浇铸法以及还原氧化石墨烯的影响

高体积比电容是柔性超级电容器的关键.在本文中,我们设计并制备了一种具有超高体积比电容和良好倍率性能的柔性复合电极.该膜电极以无孔且致密的聚苯胺作为基质,少量的还原氧化石墨烯片作为填料,通过一种新开发的溶液浇铸法制备而成.用于浇铸的溶液是由聚苯胺和氧化石墨烯的混合溶液自组装制备得到.关于还原氧化石墨烯作用的系统研究结果表...     

具有高容量和优异倍率性能的柔性超级电容器

正随着便携、可穿戴电子设备的发展,柔性的超级电容器得到越来越广泛的关注和研究,以适应不同应用领域的储能需求。在柔性超级电容器中,具有高容量、高充放电倍率性能的柔性电极材料的设计和制备至关重要。石墨烯和导电聚苯胺分别具有双电层电容和赝电容的储能特性,是两类最具代表性的超级电容器电极材料。通过在纳米     

聚苯胺复合石墨烯纳米卷的制备及其在超级电容器中的应用（英文）

石墨烯纳米卷是一种具有开放式螺旋状纳米卷结构的管状石墨烯。以石墨烯纳米卷为模板,利用原位聚合的方法,将聚苯胺生长在石墨烯纳米卷表面。通过对材料形貌进行表征,发现聚苯胺均匀地分布在石墨烯纳米卷表面。分别对3种不同单体浓度的聚苯胺复合石墨烯纳米卷进行电化学性能考察,结果发现石墨烯纳米卷和聚苯胺产生的协同效应使得复合卷在继承石墨烯纳米卷良好的倍率特性同时显著地提升了比电容,在1 A/g时比电容可达320 F/g,100A/g时仍可以保持92.1%的初始电容,为制备高比容、快速充放电的石墨烯纳米卷基超级电容器奠定了基础。     

3D-石墨烯及其聚苯胺复合材料在超级电容器中的研究进展

聚苯胺制备工艺简单,价格低廉,结构稳定,理论比容量大,掺杂过程简单,具备掺杂和反掺杂的性能,但循环稳定性差,将其与石墨烯复合,利用二者的协同作用能够更好地提高电容性能。与二维石墨烯相比,三维石墨烯具有独特的三维多孔结构,不仅增加了与电解液的接触面积,同时提供了快速的电子传输通道,而且其独特的网状结构可减少聚苯胺在复合材料中的团聚使其在超级电容器方面表现出良好的潜力。介绍了三维石墨烯的制备方法,主要包括自组装法和模板导向法;综述了三维石墨烯/聚苯胺复合材料以及掺杂改进的三维石墨烯/聚苯胺复合材料的制备方法及其电化学性能在超级电容器中的研究进展;并对其未来研究发展趋势进行了展望。     

聚苯胺/改性活性炭复合电极材料的制备及其电容性能研究

通过改变有机酸与无机酸的配比研究合成高电导率聚苯胺的最佳条件,使用硝酸对活性炭进行改性,测定活性炭的沉降质量和活化指数并筛选出吸附性能最佳的改性活性炭,将最佳工艺条件下合成的聚苯胺与改性活性炭进行复合制备了聚苯胺/改性活性炭复合电极材料。通过X射线衍射、扫描电子显微镜和电化学性能测试对复合电极材料的结构和性能进行表征和研究。结果表明:用质量分数3%的硝酸改性的活性炭掺杂聚苯胺,二者的相容性最好,且改性活性炭含量为25.5%(质量分数)时,制备的复合电极材料比电容最大,为282F/g,比纯聚苯胺的比容量(210F/g)增加了34.3%。电化学性能测试表明,聚苯胺/改性活性炭复合电极材料内阻小,阻抗高,电容性能优良。     

三维石墨烯网络在超级电容器中的应用（英文）

三维石墨烯网络(3DGNs)能够缩短电解质离子的扩散距离,提供快速电子输运通道,并能充当骨架以与赝电容材料进行复合,因而在超级电容器中得到了广泛应用。本文主要综述近年来三维石墨烯网络及其复合材料在超级电容器电极材料方面的的进展,论述提升三维石墨烯基超级电容器性能的途径,最后展望了未来三维石墨烯网络的前景。     

石墨烯基柔性一维电极材料的的制备与性能研究

在储能电子设备中,具有高柔韧性和导电性的石墨烯基电极材料在超级电容器中展现了极大的应用前景。研究采用Hummers方法制备氧化石墨烯(GO),再湿法纺丝技术制备GO纤维。进一步研究还原条件对纤维结构及性能的影响。研究发现,在90℃水合肼蒸气还原条件下,随着还原时间增加,还原越完全;但是还原时间过长,纤维的结构会出现损坏,电化学性能会有所下降。为进一步提高石墨烯纤维的电化学性能,在纤维表面和内部原位沉积聚合物-聚苯胺(PANI),制得了比电容可达到46.11 F/cm~3的石墨烯基复合纤维电极。     

以氧化石墨为基质制备石墨烯/聚苯胺复合材料及其电化学性能

利用以苯胺与过硫酸铵制备的聚苯胺和改进的Hummers法制备的氧化石墨烯(GO)为原料,将聚苯胺分散于GO浊液中,再对GO进行还原,制备超级电容器电极材料石墨烯(RGO)/聚苯胺(PANI)复合材料(GRP),利用X射线衍射(XRD)对其结构进行了表征,并对复合材料电化学性能进行了测试。结果表明,复合材料展示良好比电容特性,同时又具有稳定电化学性能。GRP在0.1A/g的电流密度下比电容达到510F/g,1.0A/g电流密度下比电容为485F/g,经过2000次的充放电循环后比电容保持率为92%,即复合物比电容远大于石墨烯,在化学稳定性上远好于PANI。放电响应效率高,在电极中电解质离子容易扩散和迁移。     

石墨烯基柔性超级电容器复合电极材料的研究进展

近年来,便携式和可穿戴电子设备呈现出跨越式发展,为了使可穿戴电子器件更加灵活、轻巧、智能并完全实现产品化,就需进一步探求与之匹配的具有薄、轻、柔特点的储能装置。超级电容器由于具有功率密度高、循环寿命长、机械强度高、安全性好和易于组装等优点,受到研究者的广泛关注。然而,传统的超级电容器一旦受到外力发生变形,储能特性会极大降低甚至丧失。电极材料是电容器的核心部分,因此研制出高柔韧性和储能特性出众的电极材料是有必要的。石墨烯因具有大比表面积,优异的力学、电学性能而成为用于柔性超级电容器的有吸引力的电极材料。赝电容材料可提供高比电容,但其导电性差、稳定性低,因此研究者将石墨烯与赝电容材料相融合作为电极材料,充分发挥各自优势,不仅克服了石墨烯片层间易团聚的缺点,还可提高柔性超级电容器的整体能量密度。由于二维石墨烯片层易堆叠,电子传导能力受到限制,目前更多的研究工作致力于三维多孔网状结构的石墨烯材料。本文突出介绍了石墨烯的两个重要角色:(1)与电化学活性物质复合作为活性材料;(2)作为沉积活性物质的导电柔性基体。因此,功能多样化的石墨烯在制备柔性电极中有很大的潜力。通过化学沉积、浸涂、水热等工艺将具有高电导率的石墨烯直接作为柔性基底,或与赝电容材料键合附着在柔性基体上,制备基于石墨烯的柔性电极材料。本文介绍了超级电容器的储能原理和石墨烯在柔性超级电容器领域的应用状况,着重总结了石墨烯/过渡金属氧化物、石墨烯/导电聚合物复合电极材料在柔性超级电容器方面的研究进展;解析了柔性超级电容器电极材料仍然面临的挑战,并对其未来的发展进行了展望。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...