碳气凝胶／H2SO4双电层电容器的特性

研究了碳气凝胶在Ｈ２ＳＯ４电解液中的电化学行为,结果表明碳气凝胶在Ｈ２ＳＯ４电解液中电化学性能稳定。用Ｈ２ＳＯ４电解液、碳气凝胶材料作电极制作双电层电容器,并用导电塑料将两个电容器串联使用,提高工作电压,用机械加压降低双电层电容器的内阻,测得的双电层电容器放电电容量约１７Ｅ,内阻力１．９５Ω,电压保持能力较好。     

煅烧温度对Li0.33La0.56TiO3固态离子电容器性能的影响

本文采用固相法在900、1000、1100和1200℃煅烧温度条件下合成了Li_0.33La_0.56TiO₃(LLTO)固态电解质材料, 并将其组装为LLTO固态离子电容器。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、电化学阻抗谱(EIS)和循环伏安法(CV)等技术研究了煅烧温度对LLTO固态电解质和固态离子电容器的显微结构、形貌、离子电导率和储能性能的影响。实验表明, 较高的煅烧温度有利于获得性能优异的LLTO固态离子电容器。在室温下, 1200℃煅烧温度制备的固态离子电容器晶粒离子电导率高达 9.6×10^-4 S/cm, 且具有明显的双电层电容特性, 在4 V电压窗口下比电容为3.52 mF/g。此外, 固态离子电容器比电容随晶粒电导率的增大而增大, 同时受电极与固态电解质接触面积的影响。     

粘结剂对块状极板碳纳米管双电层电容器性能影响研究

碳纳米管具有良好的导电性和合适的双电层形成区,适于制作双电层电容器极板． 不同粘结剂的使用会影响电容器的性能,分别选用酚醛树脂和聚四氟乙烯（ＰＴＦＥ）作为碳纳米 管极板的粘结剂,在有机电解质溶液中,研究其电容性能与比表面积和极板结构的关系,从而 找出合适的碳纳米管极板粘结剂．     

超级电容器电解质研究进展

电解质作为超级电容器的重要组成部分,对器件性能起着关键性作用。本文对近些年来超级电容器各种电解质,包括水系、有机液体、离子液体、固态/准固态聚合物电解质和氧化还原体系电解质的特点和最新研究成果进行了描述;重点介绍了固态/准固态聚合物电解质的分类及其性能研究概况。提出了发展电位窗口宽、离子电导率高、电化学性能稳定的离子液体和机械强度等综合性能优良的凝胶聚合物电解质是将来超级电容器电解质发展领域的趋势,最后对超级电容器电解质的发展前景进行了展望。     

3V、千法级超大容量电容器研究

超大容量电容器亦称双电层电容器,具有比传统电容器高得多的能量密度和比电池高得多的功率密度。采用活性炭作电极活性物质,得到单体比容量为52F·g-1,并通过并联、串联组装出了电压为3V、容量为1000F左右的超大容量电容器,经过测试得其等效串联内阻(ESR)为56mΩ,等效漏电电阻约为170Ω,漏电电流为15mA。测试了双电层电容器的充放电性能、负载性能、漏电特性等,并对双电层电容器充放电和漏电过程进行了讨论。     

基于阻燃离子凝胶电解质的高安全性柔性超级电容器（英文）

在传统的超级电容器中,有机电解质的存在导致其安全性和灵活性能差,限制了超级电容器的发展和应用.因此,我们开发了一种简易制备的具有强阻燃性、热稳定性、灵活性和电化学特性的离子凝胶超级电容器.具体来说,通过在电极上使用离子凝胶电解质的原位交联,获得了具有优良性能的离子凝胶超级电容器.在离子凝胶电解质中引入大量含醚的柔性链段后,其室温电导率可以高达6.5×10^-3 10^-3Scm^-1.同时,原位交联的制备方法使电解质和电极之间具有紧密的界面接触.由于该离子凝胶电解质具有紧密的电极/电解质界面接触和良好的机械特性,使其在弯曲时保持了稳定的电化学性能.此外,在交联的电解质中加入二氮杂萘结构为离子凝胶电解质提供了良好的阻燃性和热稳定性,使其能够在150℃下保持30分钟的尺寸稳定性.使用离子凝胶电解质制备的超级电容器的比容量为105F g^-1,能量密度为41.6 W h kg^-1.这项工作为制备和优化离子凝胶交联电解质提供了一种实用方法和新的见解.     

一种新型氧化还原活性凝胶电解质在超级电容器中的应用

以2-巯基吡啶(PySH)为氧化还原活性介质,以聚乙烯醇(PVA)为聚合物基体,采用溶液共混法制备了PVA-H2SO4-PySH凝胶电解质,研究了PySH添加量对凝胶电解质离子电导率的影响,并组装了活性炭电极超级电容器,利用循环伏安、恒流充放电、交流阻抗谱和自放电等测试对超级电容器电化学性能进行了表征。结果表明,PySH的引入提高了凝胶电解质的离子电导率,同时也改善了超级电容器的电化学性能,在相同电流密度下,超级电容器电极比电容由137F/g提高为394F/g,能量密度由3.6Wh/kg提高到12.4Wh/kg,经过3000次充放电循环后比电容保持率为89%。     

一种新型氧化还原活性凝胶电解质在超级电容器中的应用

以2-巯基吡啶(PySH)为氧化还原活性介质,以聚乙烯醇(PVA)为聚合物基体,采用溶液共混法制备了PVA-H2SO4-PySH凝胶电解质,研究了Py-SH添加量对凝胶电解质离子电导率的影响,并组装了活性炭电极超级电容器,利用循环伏安、恒流充放电、交流阻抗谱和自放电等测试对超级电容器电化学性能进行了表征。结果表明,PySH的引入提高了凝胶电解质的离子电导率,同时也改善了超级电容器的电化学性能,在相同电流密度下,超级电容器电极比电容由137F/g提高为394F/g,能量密度由3.6Wh/kg提高到12.4Wh/kg,经过3000次充放电循环后比电容保持率为89%。     

凝胶聚合物电解质组装聚3,4-乙烯二氧噻吩固态超级电容器

以聚3,4-乙烯二氧噻吩/碳纸(PEDOT/CP)为电极,聚乙烯醇/硫酸/碘化钾(PVA/H_2SO_4/KI)凝胶为聚合物电解质,组装成PEDOT固态超级电容器。采用循环伏安法(CV)、恒电流充电/放电技术(GCD)和电化学阻抗谱(EIS)技术研究了电解质中PVA浓度对超级电容器电化学性能的影响。结果表明,以浓度为10%的PVA溶液所组装的固态电容器在1 mA/cm~2放电电流下有较高的比电容(352.59 F/g),能量密度和功率密度分别为451.32 Wh/kg,13.29 kW/kg。凝胶聚合物电解质因兼具了液体电解质优良的电导率和固态电解质易于封装、无泄漏等优点,所以在电源备用系统、电动汽车、医疗电子器械及军工设备等领域中具有良好的应用前景。     

可穿戴柔性超级电容器用强韧、自修复、抗冻的三角色铁氰化钾氧化还原凝胶聚合物电解质（英文）

超级电容器的韧性、自修复和高比电容对于柔性和可穿戴电子设备具有重要的实用价值.为此,我们制备了一种新型的聚乙烯醇-海藻酸钠-铁氰化钾-硫酸钠多功能凝胶聚合物电解质.其中铁氰化钾起到了三角色作用,包括载流子供体、离子交联剂和氧化还原活性剂,有效地缓解了凝胶聚合物电解质通常存在的电导率与机械性能间的矛盾.此外,由于铁氰化钾的氧化还原反应提供了赝电容,组装的超级电容器具有很高的电极比电容和能量密度.该超级电容器还表现出优异的弯曲、拉伸、自修复和抗冻能力.因而,制备的凝胶聚合物电解质和超级电容器在复杂使用条件下的柔性和可穿戴电子设备中具有广阔的应用前景.     

Thermal conductivity of inhomogeneous materials

The effective thermal conductivity is calculated from the rate of entropy production per unit volume. Thermal conductivity and the temperature field are expressed in terms of Fourier components and these are related. The rate of entropy production is then obtained in terms of the volume-averaged thermal conductivity and the Fourier components of thermal conductivity. A simple expression for the effective thermal conductivity is found. In the case of striations it leads to well-known results. The formalism is applied to solids with inhomogeneously distributed solutes. It is shown that the thermal conductivity is less than the volume-averaged thermal conductivity and that homogenization by diffusion increases the thermal conductivity. Similar results would apply to the electrical conductivity of inhomogeneous alloys.     

纳米流体悬浮稳定性和电导率的关系研究

基于Maxwell电磁理论中电解质悬浮液中粒子质量分数和电导率之间的关系,提出了一种判定纳米流体悬浮稳定性的方法,并进行了实验验证。实验中,采用"两步法"经超声振荡制备了CuO/去离子水纳米流体。利用电导率仪测量了不同质量分数时纳米流体的电导率,建立了质量分数与电导率的关系,同时研究了温度对电导率的影响。结果表明电导率随着颗粒质量分数的增加而增加,随着质量分数的减小而减小;随着温度的增长,电导率只有微小变化,可以忽略温度对电导率的影响。     

Thermal Conductivity of Coated Paper

In this article, a method for measuring the thermal conductivity of paper using a hot disk system is introduced. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper, although it is important to various forms of today’s digital printing where heat is used for imaging, as well as for toner fusing. This motivated an investigation of the thermal conductivity of paper coating. This study demonstrates that the thermal conductivity is affected by the coating mass and the changes in the thermal conductivity affect toner gloss and density. As the coating mass increases, the thermal conductivity increases. Both the toner gloss and density decrease as the thermal conductivity increases. The toner gloss appears to be more sensitive to the changes in the thermal conductivity.     

填充型聚合物基复合材料的导电和导热性能

研究了高密度聚乙烯为基体、炭黑和炭纤维为填料复合体系的导电和导热性能。发现当导电填料的含量达到渗流阈值时,复合材料的电导率急剧升高;而在渗流阈值附近,其热导率未出现突变。这表明电导渗流现象不完全是由导电粒子通过物理接触生成导电链所致。其导电机制是相当数量的导电粒子相互发生隧道效应。     

Improvements in methods for measuring the volume conductivity of electrically conductive carbon powders

Electrically conductive carbon powders are commonly used as filler materials in polymers to create electrically semi-conductive composite materials for use in battery electrodes and anti-static applications. Current methods for characterizing the conductivity of these powders use two pistons to compress the powders. Two-piston methods are known to underestimate conductivity. This study develops a guard-electrode method based on ASTM D257 to better characterize the bulk conductivity and impedance spectra of electrically conductive powders. The conductivity and impedance spectra of a highly conductive powder (copper powder) and a low conductivity powder (cellulose) were used to bound the conductivity of carbon black, graphite, and biochar. Powders were measured through a full range of compression with both the two-piston and the guard-electrode method. In all cases, measurements using the guard-electrode method have higher conductivity and lower impedance than the same powders measured using the two-piston method. The grain conductivity of the particles is obtained through fitting the relationship of conductivity versus packing fraction using the GEM equation. The guard-electrode method is shown to be more similar to established conductivity values as measured via a four-probe technique for copper and graphite then the two-piston method.     

影响Mo-Cu合金电热性能的因素

主要叙述了适用封接用Mo-Cu导热导电性能的测定方法，论述了Cu和Ni含量对钼铜合金热电性能的影响：机械活化处理及热处理等因素对钼铜合金热电性能的影响。认为Ni等少量杂质元素的加入，Mo-Cu合金材料的热电性能降低；机械活化处理使Mo-Cu合金的热导和导电性能下降；Cu含量的加入和适当的热处理使Mo-Cu合金的热电性能提高。     

Statistical continuum theory for the effective conductivity of fiber filled polymer composites: Effect of orientation distribution and aspect ratio

Effective conductivity of polymer composites, filled with conducting fibers such as carbon nanotubes, is studied using statistical continuum theory. The fiber orientation distribution in the matrix plays a very important role on their effective properties. To take into account their orientation, shape and distribution, two-point and three-point probability distribution functions are used. The effect of fibers orientation is illustrated by comparing the effective conductivity of microstructures with oriented and non-oriented fibers. The randomly oriented fibers result in an isotropic effective conductivity. The increased fiber orientation distribution can lead to higher anisotropy in conductivity. The effect of fiber’s aspect ratio on the effective conductivity is studied by comparing microstructures with varying degrees of fiber orientation distribution. Results show that the increase in anisotropy leads to higher conductivity in the maximum fiber orientation distribution direction and lower conductivity in the transverse direction. These results are in agreement with various models from the literature that show the increase of the aspect ratio of fibers improves the electrical and thermal conductivity.     

石墨烯季戊四醇相变复合材料导热性能的分子动力学研究

低导热是限制储能材料实际应用的一大缺点,具有极高导热系数的石墨烯可作为导热填料有效改善储能材料的导热性能。本文通过反向非平衡分子动力学的方法,借助Materials Studio软件,模拟研究了石墨烯(GE)质量分数为0.5%、1%、1.5%、2%、2.5%、3%的石墨烯/季戊四醇(GE/PE)固-固相变复合材料的导热性能和内部相互作用。结果表明:石墨烯的添加可有效提升季戊四醇的导热性能,随着GE质量分数的增加,GE/PE复合相变材料的导热率、界面热导以及相互作用能均逐渐增大,且趋势幅度相一致,材料整体导热系数的增加归因于石墨烯结构的变化。本文可为石墨烯改善季戊四醇导热性的实验研究提供指导。     

Three principles for preparing Al wire with high strength and high electrical conductivity

The trade-off relation between the strength and the electrical conductivity has been a long-standing dilemma in metallic materials. In the study, three key principles, i.e. elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength; while, the 111 sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.