三维石墨烯的可压缩性能及在超级电容器中的应用

以氧化石墨烯为原料,通过水热反应和高温焙烧过程制备了三维石墨烯柱状体材料。采用机械力学测试方法分析三维石墨烯的可压缩性能,将其作为超级电容器的电极材料测试其电化学性能。结果表明,三维石墨烯呈多孔网状结构,具有良好的可压缩性能和机械性能。电极片厚度为2 mm,铝塑外包尺寸为5 cm×6 cm的对称超级电容器在电流密度为0.1 A/g下比电容为175 F/g,在电流密度为1 A/g下充放电循环10 000次后比电容保持率为81.9%。在加载不同大小压力压缩状态下,其保持了良好的电容性能。     

石墨烯/聚吡咯导电复合材料超级电容器电极的制备研究

超级电容器与锂电池相比具有更高的循环稳定性以及更高的能量密度。提高超级电容器电极材料化学稳定性,增大离子吸附比表面积,以获得更好的电化学性能,成为超级电容器研究领域的热点。以湿化学还原法制备的石墨烯为基底,采用原位电化学沉积法制成了石墨烯/聚吡咯导电复合材料超级电容器电极。通过扫描电子显微镜(SEM)对电极的微观形貌进行了观察,利用电化学工作站对组装的超级电容器电化学性能进行了系统表征,同时探讨了沉积浓度和沉积时间对电化学性能的影响。结果表明,在0.2 mol/L吡咯溶液中沉积时间为22.5 min制备出的石墨烯/聚吡咯导电复合材料电极的比电容可达388 F/g,表现出优良的超级电容器电化学性能。     

石墨烯/聚吡咯导电复合材料超级电容器电极的制备研究

超级电容器与锂电池相比具有更高的循环稳定性以及更高的能量密度。提高超级电容器电极材料化学稳定性,增大离子吸附比表面积,以获得更好的电化学性能,成为超级电容器研究领域的热点。以湿化学还原法制备的石墨烯为基底,采用原位电化学沉积法制成了石墨烯/聚吡咯导电复合材料超级电容器电极。通过扫描电子显微镜(SEM)对电极的微观形貌进行了观察,利用电化学工作站对组装的超级电容器电化学性能进行了系统表征,同时探讨了沉积浓度和沉积时间对电化学性能的影响。结果表明,在0.2mol/L吡咯溶液中沉积时间为22.5min制备出的石墨烯/聚吡咯导电复合材料电极的比电容可达388F/g,表现出优良的超级电容器电化学性能。     

绿色高效制备电化学性能优异的多孔石墨烯电极材料

电极材料的性能决定超级电容器的储能特性,因此研究优异电极材料的制备方法是提高其储能特性的重要前提。多孔石墨烯(Porous graphene)作为新型的碳材料具有比表面积大、电导率高等优点,是一种理想的双电层电容器电极材料。本工作制备的多孔石墨烯材料微孔和中孔都很发达,孔径分布更为合理,因此其比表面积相较于原始的石墨烯有了很大的提高。经检测该材料的比表面积为1 417.65 m²·g-1,并且能够提供较高的电化学双电层电容,经测试由该材料组装成的扣式超级电容具有31.7 F·g-1的比容量且具有优良的导电特性。此外,在电流密度1 A·g-1下循环10 000次后材料比电容保持率为78%。这些电化学测试结果表明本研究制备的多孔石墨烯在超级电容器的能量存储方面具有较好的应用前景。     

分级多孔活性炭的KOH再活化法制备及其电化学性能

首先利用水热法以葡萄糖为碳源合成炭微球,然后采用KOH再活化法将炭微球制备成分级多孔活性炭,最后测试并表征其作为超级电容器电极材料的电化学性能。结果表明:KOH再活化法具有扩孔和再造孔的双重作用,可获得具有较高的比表面积、合适的分级多孔结构和良好的石墨化程度的分级多孔活性炭材料;在Na2SO4中性电解液中,在电流密度为1 A/g时,分级多孔活性炭材料的比电容可达209 F/g,表现出优异的电化学性能。     

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。     

水热法合成二硫化钼花状微球及其电容性能研究

使用水热法以钼酸铵为钼源,硫脲为硫源制备了由纳米片组成的三维花状的二硫化钼微球。利用XRD、Raman、SEM和TEM对产物的微观结构和形貌进行了表征。同时通过循环伏安法、恒电流充放电和交流阻抗谱研究了其作为超级电容器电极材料的电化学性能。测试表明MoS2花状微球电极材料在电流密度为0.5A/g时,比电容可达225F/g,具有良好的倍率性能,是一种性能优异的超级电容器电极材料。     

超级电容器用石墨烯极片的制备和性能

以石墨粉为原料,通过简便的氧化还原法制备了石墨烯。将石墨烯极片在有机电解液体系中组装成超级电容器。利用XRD、SEM对制备的石墨烯电极进行物相和形貌分析。采用恒电流充放电、循环伏安和交流阻抗对所制备超级电容器的电容性能进行了研究。结果表明,石墨烯电极超级电容器比天然石墨制备的超级电容器的比电容有了明显的提高;在电流密度为200mA/g,电压区间为1.25~2.5V下循环888次后比电容保持在45.5F/g,容量保持率在85.5%,表明石墨烯材料制备的电容器具有较好的充放电循环性能。     

超级电容器用石墨烯极片的制备和性能

以石墨粉为原料,通过简便的氧化还原法制备了石墨烯。将石墨烯极片在有机电解液体系中组装成超级电容器。利用XRD、SEM对制备的石墨烯电极进行物相和形貌分析。采用恒电流充放电、循环伏安和交流阻抗对所制备超级电容器的电容性能进行了研究。结果表明,石墨烯电极超级电容器比天然石墨制备的超级电容器的比电容有了明显的提高;在电流密度为200mA/g,电压区间为1.25~2.5V下循环888次后比电容保持在45.5F/g,容量保持率在85.5%,表明石墨烯材料制备的电容器具有较好的充放电循环性能。     

用于超级电容器的高性能石墨烯/CoMoO4复合电极

高性能超级电容器电极材料的开发对于缓解当前的能源危机势在必行,设计和优化混合过渡金属氧化物并研究电化学性能和循环寿命对于超级电容器的实际应用至关重要。在已开发的混合过渡金属氧化物中,由于电活性材料的导电率差并且与电解质的接触受限制,大大限制了所制备电极的电化学性能。我们在本文中提出了一种合成石墨烯/CoMoO_4纳米片的有利设计,使活性材料均匀生长在三维石墨烯泡沫的网状骨架上,充分提高了活性材料的利用率,其独特的结构也增加了电活性材料与电解质界面之间的接触,使赝电容反应充分发生。由于石墨烯的高电子传输速率和CoMoO_4纳米片的高活性,三维复合电极具有出色的电化学性能,具有相对较高的面积比电容(在1 mA cm~(-2)下为2 737 mF cm~(-2))和出色的循环稳定性(在10 mA cm~(-2)下进行4000次循环后,保留原始比电容的81.76%)。这些出色的结果表明,石墨烯/CoMoO_4纳米片复合材料具有巨大的潜力,可作为高性能超级电容器的电极材料。     

三维石墨烯及其复合材料的制备及在超级电容器中的研究进展

三维(3D)石墨烯及其复合材料具有柔韧性好、比表面积大、功率密度高、力学性能稳定以及离子传输迅速等优良性能,成为材料科学领域备受关注的材料。概述了三维石墨烯材料的基本性质和性能,并对其多元复合材料的制备方法以及在超级电容器储能材料方面的应用研究进展进行了评述。三维(3D)石墨烯常用的制备方法有自组装法、模板导向法和3D打印法等,通过对制备方法进行改进,可以有效调控三维材料的多孔结构、孔径、柔韧性和电子传递速度等性能。三维(3D)石墨烯与过渡金属化合物及导电聚合物复合而成的多元复合物在超级电容器电极材料方面表现出广阔的应用前景。     

Chemical adsorption of NiO nanostructures on nickel foam-graphene for supercapacitor applications

Few-layer graphene was synthesized on a nickel foam template by chemical vapor deposition. The resulting three-dimensional (3D) graphene was loaded with nickel oxide nanostructures using the successive ionic layer adsorption and reaction technique. The composites were characterized and investigated as electrode material for supercapacitors. Raman spectroscopy measurements on the sample revealed that the 3D graphene consisted of mostly few layers, while X-ray diffractometry and scanning electron microscopy revealed the presence of nickel oxide. The electrochemical properties were investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and potentiostatic charge–discharge in aqueous KOH electrolyte. The novelty of this study is the use of the 3D porous cell structure of the nickel foam which allows for the growth of highly conductive graphene and subsequently provides support for uniform adsorption of the NiO onto the graphene. The NF-G/NiO electrode material showed excellent properties as a pseudocapacitive device with a high-specific capacitance value of 783 F g^?1 at a scan rate of 2 mV s^?1. The device also exhibited excellent cycle stability, with 84 % retention of the initial capacitance after 1000 cycles. The results demonstrate that composites made using 3D graphene are versatile and show considerable promise as electrode materials for supercapacitor applications.     

Making a wearable supercapacitor based on highly porous 3D nitrogen-doped graphene

In this paper, based on the hydrothermal method and using a non-toxic organic molecule, as a spacer (and nitrogen source), we synthesized a highly conductive and porous 3D graphene. Then, graphene is used as an electrode material to make a supercapacitor on the surface of activated carbon cloth electrode. The graphene is characterized by different methods, such as Fourier-transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, X-ray diffraction, energy-dispersive and transmission electron microscopy, energy-dispersive X-Ray spectroscopy, emission scanning electron microscopy, Barrett–Joyner–Halenda, and Brunauer–Emmett–Teller methods. The supercapacitor (2 and 3 electrodes) is studied by different electrochemical techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge. The 3-electrode system shows a specific capacity 101 F g^? 1 at the current density of 1.7 A g^? 1 (or 0.5 mA cm^? 2). The 2-electrode system (symmetric capacitor) has a power density of about 8000 W kg^? 1 and a maximum energy density of 12.85 Wh kg^? 1.

     

Ni2CoS4/还原氧化石墨烯/多孔还原氧化石墨烯的制备及其在超级电容器中的应用

采用水热法制备Ni_2CoS_4活性材料,通过物理过程和水热反应将其与氧化石墨烯(GO)、水热多孔氧化石墨烯(HHGO)复合得到Ni_2CoS_4/还原氧化石墨烯/多孔还原氧化石墨烯(Ni_2CoS_4/RGO/HRGO)复合电极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、循环伏安测试、恒流充放电测试和交流阻抗测试等,对复合材料的形貌结构、电化学性能进行了表征。研究结果表明:在1 A/g的电流密度下,其比电容为1 684 F/g,在5 A/g的电流密度下循环2 000次后,其比电容保持率为91.8%。Ni_2CoS_4/RGO/HRGO优良的电化学行为归因于这种复合结构使电解液对电极材料的润湿程度提高,进而提高了离子和电荷的传输速率,同时也缓解石墨烯、Ni_2CoS_4的团聚和循环过程中的体积变化。因此,Ni_2CoS_4/RGO/HRGO是一种有良好应用前景的高性能超级电容器电极材料。     

A facile preparation of pomegranate-like porous carbon by carbonization and activation of phenolic resin prepared via hydrothermal synthesis in KOH solution for high performance supercapacitor electrodes

High electrochemical performance pomegranate-like porous carbon was synthesized by the carbonization and activation of phenolic resin which was prepared by adding phenolic resin monomer mixture into KOH aqueous solution and hydrothermal treatment. In the process of hydrothermal, KOH solution could hinder the polymerization of phenolic resin monomer to form big phenolic resin particles. During the carbonization, phenolic resin plays the role of forming small particles and binder during carbonization, which can simultaneously achieve high specific surface area and form three dimensional structures to improve the conductivity. The results showed that pomegranate-like porous carbon composed of small nanometer-scale particles was observed. The obtained porous carbon electrode materials had a high content of micropores with specific surface area as high as 2199.9 m² g⁻¹. The porous carbon exhibited a high specific capacitance of 341.3 F g⁻¹ at 0.1 A g⁻¹, good rate capability with 71.0% retention from 0.1 to 5 A g⁻¹. Moreover, it showed high capacitance retention of 96.1% after 5000 cycles at a scan rate of 50 mV s⁻¹, indicating excellent cycling stability. The assembled symmetrical supercapacitor showed high energy densities of 17.0 Wh kg⁻¹ and 8.5 Wh kg⁻¹ with the corresponding power densities of 49.6 W kg⁻¹ and 1.8 kW kg⁻¹, respectively. The facile method could be a promising candidate for preparing porous carbon electrode materials with excellent electrochemical performance in the fields of supercapacitors.     

Ag-doped NiO porous network structure on Ni foam as electrode for supercapacitors

Ag-doped NiO porous network structure grown on Ni foam has been synthesized through a facile hydrothermal method. Then network structure is assembled by numerous interconnected superfine nanowires, and Ag is uniformly distributed in the body of NiO network. The unique porous network structure doped by conductive Ag and the direct integration of electrode materials on Ni foam current collector provide efficient pathways for electron transport and electrolyte ions diffusion. The electrochemical results demonstrate that the Ag-doped NiO electrode exhibits a specific capacitance of 570.7 F g^?1 and excellent cycling stability. The Ag-doped NiO electrode with relatively high electrochemical performance is a promising candidate for the supercapacitor electrodes. These results can also provide strategies to develop advanced electrode materials supercapacitor applications.     

中间相沥青基活性泡沫炭的制备及其电化学性能研究

以中间相沥青为前驱体,经自挥发发泡法、KOH活化法制备的中间相沥青基活性泡沫炭作为超级电容器电极材料。采用扫描电镜、X射线衍射和低温(77K)N2吸附法对中间相沥青基活性泡沫炭的表面形貌和微观结构进行表征。中间相沥青基活性泡沫炭的比表面积为2700m2/g,总孔孔容为1.487cm3/g。通过恒流充放电、循环伏安和交流阻抗测试,考察了中间相沥青基活性泡沫炭作为超级电容器电极材料的电化学性能。在电流密度为0.02A/g时,中间相沥青基活性泡沫炭的比容量为240.48F/g,能量密度为33.4Wh/kg;在电流密度为5A/g时,比容量为166.68F/g,具有良好的电化学特性。     

One-step strategy to graphene/Ni(OH)2 composite hydrogels as advanced three-dimensional supercapacitor electrode materials

Graphene-based three-dimensional (3D) macroscopic materials have recently attracted increasing interest by virtue of their exciting potential in electrochemical energy conversion and storage. Here we report a facile one-step strategy to prepare mechanically strong and electrically conductive graphene/Ni(OH)₂ composite hydrogels with an interconnected porous network. The composite hydrogels were directly used as 3D supercapacitor electrode materials without adding any other binder or conductive additives. An optimized composite hydrogel containing ～82 wt.% Ni(OH)₂ exhibited a specific capacitance of ～1,247 F/g at a scan rate of 5 mV/s and ～785 F/g at 40 mV/s (～63% capacitance retention) with excellent cycling stability. The capacity of the 3D hydrogels greatly surpasses that of a physical mixture of graphene sheets and Ni(OH)₂ nanoplates (～309 F/g at 40 mV/s). The same strategy was also applied to fabricate graphene-carbon nanotube/Ni(OH)₂ ternary composite hydrogels with further improved specific capacitances (～1,352 F/g at 5 mV/s) and rate capability (～66% capacitance retention at 40 mV/s). Both composite hydrogels obtained here can deliver high energy densities (～43 and ～47 Wh/kg, respectively) and power densities (～8 and ～9 kW/kg, respectively), making them attractive electrode materials for supercapacitor applications. This study opens a new pathway to the design and fabrication of functional 3D graphene composite materials, and can significantly impact broad areas including energy storage and beyond.      

Direct Induction of Porous Graphene from Mechanically Strong and Waterproof Biopaper for On-Chip Multifunctional Flexible Electronics

Graphene with a 3D porous structure is directly laser-induced on lignocellulosic biopaper under ambient conditions and is further explored for multifunctional biomass-based flexible electronics. The mechanically strong, flexible, and waterproof biopaper is fabricated by surface-functionalizing cellulose with lignin-based epoxy acrylate (LBEA). This composite biopaper shows as high as a threefold increase in tensile strength and excellent waterproofing compared with pure cellulose one. Direct laser writing (DLW) rapidly induces porous graphene from the biopaper in a single step. The porous graphene shows an interconnected carbon network, well-defined graphene domains, and high electrical conductivity (e.g., ≈3 Ω per square), which can be tuned by lignin precursors and loadings as well as lasing conditions. The biopaper in situ embedded with porous graphene is facilely fabricated into flexible electronics for on-chip and paper-based applications. The biopaper-based electronic devices, including the all-solid-state planer supercapacitor, electrochemical and strain biosensors, and Joule heater, show great performances. This study demonstrates the facile, versatile, and low-cost fabrication of multifunctional graphene-based electronics from lignocellulose-based biopaper.     

Porous graphene paper for supercapacitor applications

Graphene paper shows a great promise for the electrical energy storage. However, the high stability, purity and specific surface area have become stringent requirements for supercapacitor applications. Finding methods to tackle these problems is rather challenging. Here, we develop a facile method to prepare porous graphene papers with a thickness 0.5 mm by a thermal shock to the layer-structure graphene paper self-assembled on Cu foil under nitrogen flowing. The as-prepared porous graphene paper exhibits a large specific capacitance of 100 F g~(-1)at the scan rate of 100 m V s~(-1)with high stability and purity without any residual chemical reagents, showing a promising potential for supercapacitor applications. The high electrochemical properties are mainly attributed to the high-specific area and the improved conductivity of the porous graphene paper performed by the multieffect of reducing, cleaving and expanding to the layer-structure graphene paper by high-energy thermal heating during the thermal shock process. This work paves a pathway to the facile preparation of porous graphene paper for supercapacitor applications.