20伏高电压型碳纳米管超级电容器的研制

通过催化裂解法制备了碳纳米管并进一步制备了碳纳米管膜片式电极.基于该种材料的超级电容器电极比容量达到42F/g并表现出良好的大电流放电特性.本文采用多种研究方法对基于该种材料的双电层电容器的电化学特性进行了详细的研究.本文还开发了全新的超级电容器组装工艺,采用该工艺组装的碳纳米管超级电容器工作电压可以达到20V并具有良好的容量特性和阻抗特性.     

碳纳米管-氢氧化镍复合电极电化学电容器

采用催化裂解法制备了碳纳米管并进一步制备了碳纳米管薄膜电极。基于该种材料的超电容器电极比容量为36 F/g。研究了在碳纳米管薄膜基体上使用电化学方法沉积氢氧化镍的新工艺,制备出碳纳米管/氢氧化镍复合电极。伏安特性曲线以及直流充放电实验证明复合电极的单电极比容量达到63 F/g,交流阻抗谱证明复合电极具有优良的阻抗特性。     

电子元件、组件

TM53 2004020521碳纳米管超电容器组装工艺的初步探讨/王晓峰,王大志,梁吉(清华大学)11电源技术一2003,27(5)一451一454通过催化裂解法制备了碳纳米管并采用超声震荡的方法制备成板式碳纳米管电极碳纳米管材料比容量为39F·g一1,并表现出良好的功率特性.阻抗测试表明球模处理可以较明显地降低碳纳米管材料的电阻.采用多种研究方法对基于该种材料的超电容器的电化学特性进行了详细研究,并采用“Transmission line model’,模型对电极的多孔结构进行了模拟还介绍了两种超电容器组装工艺并根据该工艺制备了工型和H型碳纳米管超电容器,两种超…     

碳纳米管/氧化镍复合电极超大容量离子电容器

碳纳米管作为一种新型碳材料,具有质轻,高的有效比表面积和优良的导电性,是制备双电层电容器较为理想的电极材料。本文实验用硝酸回流处理碳纳米管,对其表面改性,通过sol-gel法在改性后的碳纳米管上沉积Ni(OH)2,经灼烧得到碳纳米管/氧化镍复合材料,制成电极装配成电容器单元。该电容器具有双电层电容和赝电容特性,其比电容量为160 F/g,频率响应特性较活性炭电极电容器有所提高,是一种极具发展潜力的储能器件。     

多壁碳纳米管/棉织物复合柔性电极的制备

近年来柔性超级电容器在柔性电子设备领域起到越来越重要的作用,其中电活性材料与织物的结合是制备柔性电极的关键。本文针对棉织物进行多壁碳纳米管的高密度堆积性研究,并进行循环伏安曲线测试、充放电测试和交流阻抗测试。研究表明,该复合材料具备电极的应用性质,以及良好的循环稳定性和弯曲性,为进一步制备高电容量的柔性超级电容器打下了基础。     

双电层电容器碳纳米管固体极板的制备

本文研究了基于碳纳米管的法拉级双电层电容器极板的制备,使用碳纳米管和酚醛树脂混合成型作为极板的双电层电容器获得了15~25F/g的容量.通过测试所制电容器的主要电性能参数并与传统的活性炭极板对比,表明具有高的比表面积和良好晶化程度的碳纳米管用以制备双电层电容器极板具有潜在的优势.     

碳纳米管作为超大容量离子电容器电极的研究

本文采用碳纳米管作为超大容量离子电容器的电极材料,研究了硝酸改性处理、粘结剂对电极的电容器性能的影响,探讨了其电容的形成机理.当用硝酸改性处理的碳纳米管作电极,用30%(wt)的H₂SO₄作电解质溶液时,所得超大容量离子电容器不仅能形成双电层电容,也能形成赝电容,从而得到了69F/g的比电容;同时碳纳米管电极超大容量离子电容器具有良好的频率响应特性.     

超级电容器用氧化钌及其复合材料的研究进展

介绍了超级电容器(亦称电化学电容器)中赝电容器的工作原理和特点。对性能较好的电极材料氧化钌及其复合材料进行分类。综述了近年来其制备和应用进展,并针对氧化钌材料的高成本,提出解决方法和建议。最后对氧化钌材料的发展前景作了展望。     

大容量碳纳米管极板双电层电容器的研制

碳纳米管具有良好的导电性和合适的孔径分布以及较高的比表面积。选用聚四氟乙烯(PTFE)作为碳纳米管极板的粘结剂,网络结构的泡沫镍作为集流体,在有机电解质溶液中,通过直流充放电、恒功率充放电、循环伏安特性和自放电测试等实验,显示了本实验室制备的碳纳米管材料组装的双电层电容器具有良好的电化学性能。电容器中碳纳米管比电容量达74.1 F/g,比能量达16.1 Wh/kg,在自放电特性测试过程中,电容器漏电流稳定在2 mA左右。     

微波法制备超级电容器用高性能活性炭电极材料

以石油焦为原料,KOH为活化剂,经微波加热活化,制备出了超级电容器用高性能活性炭电极材料。以制得的活性炭制成的电极片为电极,6mol/L的KOH溶液为电解液,组装了模拟电容器。研究了加热时间和碱焦比对活性炭比表面积及电容器性能的影响。研究表明:在KOH与石油焦按3∶1的质量比混合,微波辐射时间为15min时,制备的活性炭比表面积达2683m2/g,模拟电容器单电极比电容量达361F/g。     

Biosensing Properties of TitanateNanotube Films: Selective Detection of Dopamine in the Presence of Ascorbate and Uric Acid

A novel strategy based on titanate nanotubes (TNTs) for developing an electrochemical biosensor is proposed. Stable TNT films are fabricated on glassy carbon (GC) electrodes by a casting technique. Cyclic voltammetry, electrochemical impedance spectrometry, and linear‐sweep voltammetry are used to characterize the TNT membrane‐covered GC electrodes (TNT/GCs). The TNT film is shown to demonstrate selectivity by charge exclusion. The TNT film is also shown to be capable of improving the mass transport to the electrode surface and electron transfer between dopamine (DA) and the electrode. Therefore, DA exhibits a quasireversible electrochemical reaction at the TNT/GC electrode. The voltammetric signal of DA is well resolved from those of ascorbate (AA) and uric acid (UA) at the TNT/GC electrode; therefore, DA can be selectively detected in the presence of a large excess of AA and UA at physiological pH. The linear calibration curve for DA is obtained over the concentration range 0.1–30 μM in a physiological solution that contains 0.1 mM AA and 0.3 mM UA.     

碳纳米管电极上的电化学行为分析

用化学方法对碳纳米管进行表面处理 ,用红外谱对处理后的碳纳米管进行表征 ,处理后的碳纳米管表面出现了活性功能团羧基。用这些碳纳米管制成电极 ,对Cd离子在硫酸钠中的电化学行为进行了分析。结果表明 ,从碳纳米管电极上可以观察到很好的、准可逆循环伏安图 ;在扫描速度为 10 0mV·s- 1时 ,氧化还原峰电位分别出现在 - 0 .6 5V和 - 0 .95V对照饱和甘汞电极(SCE)。峰电流与扫描速度的平方根成良好的线性关系 ,说明反应过程是由镉离子的扩散控制的。由循环伏安图相关的电位与扫描速度关系 ,我们导出了电子转移动力学速度参数。由于碳纳米管电极有很好的电化学活性和可重复性 ,它可以成为一种新型的分析电极材料     

An Integrated Free‐Standing Flexible Electrode with Holey‐Structured 2D Bimetallic Phosphide Nanosheets for Sodium‐Ion Batteries

An integrated, free‐standing, and binder‐free type of flexible anode electrode is fabricated from numerous holey‐structured, 2D nickel‐based phosphide nanosheets connected with carbon nanotubes. This electrode architecture can not only uniformly disperse the nanosheets throughout the whole electrode to avoid aggregation or detachment, but also provide an ideal sodium ion and electrolyte diffusion and penetration network with high electronic conductivity. Meanwhile, bimetallic phosphide formation by introducing secondary metal species will lead to a synergistic effect to modify the electrochemical properties. Due to the excellent compositional and structural characteristics of this electrode, it delivers superior performance. This designed flexible anode with Ni_1.5Co_0.5P_x nanosheets demonstrates a reversible capacity of 496.4 mAh g^?1 at 0.5 C and a good rate capacity of 276.1 mAh g^?1 at 8 C. Meanwhile, this connected integrated network woven from carbon nanotubes can effectively restrain volumetric expansion and shrinkage, and affect the conversion reaction products formation as well, from large‐sized microspheres to film structure, which is primarily credited with the improvement in electrochemical performance. This work may open up a new path for the synthesis of morphology‐controlled phosphides and promote the further development of flexible devices.     

Nanoporous Membrane Electrodes with an Ordered Array of Hollow Giant Carbon Nanotubes

This study proposes a next-generation model membrane electrode for fundamental electrochemical research of amorphous-based porous carbon materials. This novel electrode is fabricated by the uniform carbon coating of anodic aluminum oxide formed on an Al substrate and free from a barrier layer. The conformally carbon-coated layer forms vertically aligned giant carbon nanotubes, and their walls comprise low-crystalline stacked graphene sheets. The diameter and the length of the nanopores can be tuned over a broad range of between 10 to 200 nm and 2 to 90 µm, respectively. Moreover, unlike composite electrodes made from other ordered nanoporous carbons, this model electrode exhibits an absence of inter-particle spacing and hence no contact resistance between particles. Thus, this model electrode provides representative nanopores of low-crystalline carbon materials. An atomic-scale structural model of the low-crystalline carbon walls is built with the aid of an in-house temperature-programmed desorption system to enable theoretical simulations to be performed. Using this model electrode, the electrical conductivity of low-crystalline carbon walls and mass transportation in an electric double-layer system are elucidated. This representative model electrode is expected to help clarify the complex electrochemical processes in porous carbon electrodes.     

Flexible light-emitting electrochemical cells with single-walled carbon nanotube anodes

In this work, we demonstrate flexible solution processed light emitting electrochemical cells (LECs) which use single-walled carbon nanotubes (SWCNTs) films as the substrate. The SWCNTs were synthesized by an integrated aerosol method and dry-transferred on the plastic substrates at room temperature. The addition of a screen printed poly (3,4-ethylene dioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS) film onto the nanostructured electrode further homogenizes the surface and enlarges the work function, enhancing the hole injection into the active layer. By using an efficient phosphorescent ionic transition metal complex (iTMC) as the active material, efficacies up to 9 cd/A have been obtained. These values are among the highest reported so far for light-emitting diodes employing CNTs as transparent electrode.     

Flexible Hybrid Paper Made of Monolayer Co3O4 Microsphere Arrays on rGO/CNTs and Their Application in Electrochemical Capacitors

A facile one‐step hydrothermal method is developed for large‐scale production of well‐designed flexible and free‐standing Co₃O₄/reduced graphene oxide (rGO)/carbon nanotubes (CNTs) hybrid paper as an electrode for electrochemical capacitors. Densely packed unique Co₃O₄ monolayer microsphere arrays uniformly cover the surface of the rGO/CNTs film. The alkaline hydrothermal treatment leads to not only the deposition of Co₃O₄ microspheres array, but also the reduction of the GO sheets at the same time. The unique hybrid paper is evaluated as an electrode for electrochemical capacitors without any ancillary materials. It is found that the obtained hybrid flexible paper, composed of Co₃O₄ microsphere array anchored to the underling conductive rGO/CNTs substrate with robust adhesion, is able to deliver high specific capacitance with excellent electrochemical stability even at high current densities, suggesting its promising application as an efficient electrode material for electrochemical capacitors.     

Multifunctional Nanobiomaterials for Neural Interfaces

Neural electrodes are designed to interface with the nervous system and provide control signals for neural prostheses. However, robust and reliable chronic recording and stimulation remains a challenge for neural electrodes. Here, a novel method for the fabrication of soft, low impedance, high charge density, and controlled releasing nanobiomaterials that can be used for the surface modification of neural microelectrodes to stabilize the electrode/tissue interface is reported. The fabrication process includes electrospinning of anti‐inflammatory drug‐incorporated biodegradable nanofibers, encapsulation of these nanofibers by an alginate hydrogel layer, followed by electrochemical polymerization of conducting polymers around the electrospun drug‐loaded nanofibers to form nanotubes and within the alginate hydrogel scaffold to form cloud‐like nanostructures. The three‐dimensional conducting polymer nanostructures significantly decrease the electrode impedance and increase the charge capacity density. Dexamethasone release profiles show that the alginate hydrogel coating slows down the release of the drug, significantly reducing the burst effect. These multifunctional materials are expected to be of interest for a variety of electrode/tissue interfaces in biomedical devices.     

The Effect of Morphological Modification on the Electrochemical Properties of SnO2 Nanomaterials

The electrochemical performances of 1D SnO₂ nanomaterials, nanotubes, nanowires, and nanopowders, are compared to define the most favorable morphology when SnO₂ nanomaterials are adopted as the electrode material for lithium‐ion batteries. Changes in the morphology of SnO₂ are closely related with its electrochemical performance. Some SnO₂ nanomaterials feature not only an increased energy density but also enhanced Li⁺ transfer. The correlation between the morphological characteristics and the electrochemical properties of SnO₂ nanomaterials is discussed. The interesting electrochemical results obtained here on SnO₂ nanomaterials indicate the possibility of designing and fabricating attractive nanostructured materials for lithium‐ion batteries.     

Organic Semiconductor Nanotubes for Electrochemical Devices

Electrochemical devices that transform electrical energy to mechanical energy through an electrochemical process have numerous applications ranging from robotics and micropumps to microlenses and bioelectronics. To date, achievement of large deformation strains and fast responses remains challenging for electrochemical actuators wherein drag forces restrict the device motion and electrode materials/structures limit the ion transportation. Results for electrochemical actuators, electrochemical mass transfers, and electrochemical dynamics made from organic semiconductors (OSNTs) are reported. The OSNTs device exhibits high-performance with fast ion transport and accumulation in liquid and gel-polymer electrolytes. This device demonstrates an impressive performance, including low power consumption/strain, a large deformation, fast response, and excellent actuation stability. This outstanding performance stems from the enormous effective surface area of nanotubes that facilitates ion transport and accumulation resulting in high electroactivity and durability. Experimental studies of motion and mass transport are utilized along with the theoretical analysis for a variable–mass system to establish the dynamics of the device and to introduce a modified form of Euler-Bernoulli's equation for the OSNTs. Ultimately, a state-of-the-art miniaturized device composed of multiple microactuators for potential biomedical applications is demonstrated. This work provides new opportunities for next-generation actuators that can be utilized in artificial muscles and biomedical devices.     

Voltage polarity relay-optimal control of electrochemical ureaoxidation [hemodialysis application]

Voltage polarity relay (VPR) is shown to optimize the urea oxidation rate and urea current utilization under constant current conditions in direct electrochemical urea oxidation. Direct electrochemical urea oxidation is characterized by reversible deactivation of the working electrode due to oxidation products remaining on the surface and the requirement that the working electrode potential remain below about 1.1 V relative to Ag/AgCl in order to prevent undesirable secondary electrochemical oxidations. The VPR method monitors the potential of the working electrode relative to a suitable reference and changes system polarity when the upper potential set limit is reached. Thus, what was the working electrode becomes the counter electrode and vice versa. Since urea oxidation products are desorbed from the counter electrode when its potential drops below about -0.6 V relative to Ag/AgCl, alternating electrode functions between working and counter provides cyclic electrode regeneration and continuous urea oxidation. VPR is believed to optimize constant current control for any electrochemical system that exhibits behavior similar to direct electrochemical urea oxidation.