Carbon Nanotube Fibers Decorated with MnO2 for Wire-Shaped Supercapacitor

Fibers made from CNTs (CNT fibers) have the potential to form high-strength, lightweight materials with superior electrical conductivity. CNT fibers have attracted great attention in relation to various applications, in particular as conductive electrodes in energy applications, such as capacitors, lithium-ion batteries, and solar cells. Among these, wire-shaped supercapacitors demonstrate various advantages for use in lightweight and wearable electronics. However, making electrodes with uniform structures and desirable electrochemical performances still remains a challenge. In this study, dry-spun CNT fibers from CNT carpets were homogeneously loaded with MnO₂ nanoflakes through the treatment of KMnO₄. These functionalized fibers were systematically characterized in terms of their morphology, surface and mechanical properties, and electrochemical performance. The resulting MnO₂–CNT fiber electrode showed high specific capacitance (231.3 F/g) in a Na₂SO₄ electrolyte, 23 times higher than the specific capacitance of the bare CNT fibers. The symmetric wire-shaped supercapacitor composed of CNT–MnO₂ fiber electrodes and a PVA/H₃PO₄ electrolyte possesses an energy density of 86 nWh/cm and good cycling performance. Combined with its light weight and high flexibility, this CNT-based wire-shaped supercapacitor shows promise for applications in flexible and wearable energy storage devices.     

Enhanced Energy Density of Coaxial Fiber Asymmetric Supercapacitor Based on MoS2@Fe2O3/Carbon Nanotube Paper and Ni(OH)2@NiCo2O4/Carbon Nanotube Fiber Electrodes

Fiber supercapacitors are promising energy storage devices for potential application in wearable and miniaturized portable electronics, which currently suffer from difficulties in achieving high capacitance and energy density synchronously owing to the limited specific surface area of the electrode materials and material incompatibility between the two electrodes. Herein, a strategy is developed for the manufacture of coaxial asymmetric fiber supercapacitors by wrapping a core of PVA-KOH gel electrolyte-coated Ni(OH)₂@NiCo₂O₄/CNT fibers with MoS₂@Fe₂O₃/CNT paper. The as-prepared coaxial fiber asymmetric supercapacitors exhibit a specific capacitance of 373 mF cm⁻² (at a current density of 2 mA cm⁻²) and energy density of 0.13 mW h cm⁻² (at a power density of 3.2 mW cm⁻²), and also show good rate capability, long cycle life, and excellent flexibility. This work provides the possibility for the practical application of fiber supercapacitors in wearable and portable energy storage equipment.     

基于活化多孔碳负载聚苯胺正极和活化多孔碳负极的有机非对称超级电容器

采用KOH活化法制得高比表面积的活化多孔碳(aHPC),借助原位化学氧化法制得疏松多孔的活化多孔碳负载聚苯胺纳米复合材料(aHPC@PANI),并分别以aHPC及aHPC@PANI为负极与正极,以四乙基氟硼酸-乙腈为电解液,构建有机非对称超级电容器。电化学测试结果显示:在1A/g电流密度下,aHPC@PANI正极与aHPC负极分别呈现256.7F/g(-0.6~0.8V)及152.4F/g(-2~-0.6 V)的比容量;所组装的有机非对称电容器呈现宽电位窗口(2.8V),高的能量密度(在0.75kW/kg功率密度下为56.2 W·h/kg)及优异的循环稳定性(循环5 000次后其比电容保持率高达92.4%)。     

氢氧化钾活化制备超级电容器多孔碳电极材料

具有高比表面积、良好导电性的多孔碳材料在超级电容器中有着广泛的应用前景. 大量的研究工作致力于通过物理或者化学手段合成并调控多孔材料的微观结构. 在众多多孔碳材料的制备方式中,氢氧化钾作为一种高效的活化剂,常用于制备具有良好孔径分布和高比表面积多孔碳电极材料. 本文主要结合作者课题组的研究工作,着重概述利用氢氧化钾活化sp²碳纳米材料制备多孔碳材料的机理过程、结构形貌的转变以及所得材料的电化学性能,希望对发展新型的高性能基多孔碳材料的超级电容器电极材料有所帮助.     

Flower-like Highly Open-Structured Binder-Free Zn-Co-Oxide Nanosheet for High-Performance Supercapacitor Electrodes

Scientific research is being compelled to develop highly efficient and cost-effective energy-storing devices such as supercapacitors (SCs). The practical use of SC devices is hindered by their low energy density and poor rate capability due to the binding agents in fabricating electrodes. Herein, we proposed flower-like highly open-structured binder-free ZnCo₂O₄ micro-flowers composed of nanosheets supported in nickel foam (ZnCoO@NF) with improved rate capability up to 91.8% when current varied from 2 to 20 A·g⁻¹. The ZnCoO@NF electrode exhibited a superior specific capacitance of 1132 F·g⁻¹ at 2 A·g⁻¹ and revealed 99% cycling stability after 7000 cycles at a high current density of 20 A·g⁻¹. The improved performance of the ZnCoO@NF electrode is attributed to the highly stable structure of the micro/nano-multiscale architecture, which provides both the high conduction of electrons and fast ionic transportation paths simultaneously.     

尖晶石型LiMn2O4的制备及超级电容性能研究

采用高温固相法制备LiMn₂O₄。X射线衍射结果表明800 ℃下得到尖晶石型LiMn₂O₄。利用恒流充放电、循环伏安和交流阻抗等研究了LiMn₂O₄电极材料在2 mol·L^-1 (NH₄)₂SO₄溶液中的超级电容性能。循环伏安测试结果表明LiMn₂O₄电极材料在0～1 V电位窗口范围内具有较好的方形特征；恒流充放电结果表明充放电曲线呈现出较规整的三角形对称分布，放电曲线呈直线关系，5 mA·cm^-2下的放电比容量为141 F·g^-1，具有较高的充放电效率，循环性能稳定；交流阻抗结果也显示LiMn₂O₄电极材料在2 mol·L^-1 (NH₄)₂SO₄中具有典型的电容阻抗特性。     

Mesoporous Manganese Oxide/Lignin-Derived Carbon for High Performance of Supercapacitor Electrodes

This study explores the modification of lignin with surfactants, which can be used as a template to make mesoporous structures, and can also be used in combination with manganese oxide to produce manganese oxide/lignin-derived carbon. Organosolv extraction, using ethanol (70%) at 150 °C, was carried out to extract lignin from oil palm wood. Lignin was then mixed with Pluronic F-127, with and without Mn(NO₃)₂, and then crosslinked with acidic formaldehyde, resulting in a carbon precursor-based modified lignin. Carbonization was carried out at 900 °C to produce lignin-derived carbon and manganese oxide/lignin-derived carbon. The characterization materials included Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope-energy dispersive X-ray (SEM-EDX) mapping, X-ray diffraction (XRD), and N₂-sorption analysis. FTIR curves displayed the vibration bands of lignin and manganese oxide. SEM images exhibited the different morphological characteristics of carbon from LS120% (lignin with a Pluronic surfactant of 120%) and LS120%Mn20% (lignin with a Pluronic of 120% and Mn oxide of 20%). Carbon LS120% (C-LS120%) showed the highest specific surface area of 1425 m²/g with a mean pore size of 3.14 nm. The largest mean pore size of 5.23 nm with a specific surface area of 922 m²/g was exhibited by carbon LS120%-Mn20% (C-LS120%-Mn20%). C-LS120%Mn20% features two phases of Mn oxide crystals. The highest specific capacitance of 345 F/g was exhibited by C-LS120%-Mn20%.     

结晶度与粘合剂对多孔钴酸镁超电容电极能量传递效率的影响

通过热解晶态的双金属配位聚合物前驱体得到镁/钴三元氧化物、多孔MgCo_2O_4纳米结构。研究表明,不同的水热反应时间产生具不同结晶度的同构前驱体,并且当热解温度与粘合剂分别选择500℃和聚四氟乙烯(PTFE)时,便可以获得具有好的能量传递效率(η)的最优电容量。相应的具有高比表面积与适中结晶度的Mg Co_2O_4电极材料具有最大电容量(348 F·g~(-1)),η值可达92.9%,经历1 000次循环后电容量保持率为93.7%的优异电化学性能。     

Controllable Preparation of Polyaniline–Graphene Nanocomposites using Functionalized Graphene for Supercapacitor Electrodes

In order to explore the effect of graphene surface chemistry on electrochemical performance based on polyaniline–graphene hybrid material electrodes, four different polyaniline–graphene nanocomposites were fabricated with graphene oxide, reduced graphene oxide, aminated graphene and sulfonated graphene as carriers, respectively. The nanocomposites feature various structures and morphologies, which could be used to more deeply understand the morphology and structure effects caused by surface chemistry on electrochemical performance. The experimental results reveal that functionalized electronegative graphene was conducive to the vertical and neat growth of polyaniline (PANI) nanorods. The array architecture endowed the PANI–GS nanocomposite with a large ion‐accessible surface area and high‐efficiency electron‐ and ion‐transport pathways. Meanwhile, the introduction of sulfonic acid functional groups accelerated the redox reaction with doping and dedoping of the PANI. Thereby, the PANI–GS nanocomposite exhibited a high specific capacitance of 863.2 F g^?1 at a current density of 0.2 A g^?1 and the excellent rate capability of 67.4 % (581.6 F g^?1 at 5 A g^?1), which were much better than the other three nanocomposites produced.     

零维/二维MXene复合膜的制备及其超级电容器性能

采用水热法制备了0D/2D复合Ti₃C₂T_x MXene,利用X射线衍射、动态光散射和荧光光谱表征了其结构与形貌,结果表明形成了量子点吸附于纳米片的Ti₃C₂T_x复合结构（QDT）。相比未引入量子点的Ti₃C₂T_x,由QDT组装得到的自支撑膜电极的电化学性能有了显著提高：在三电极体系中,扫速为5 mV·s^-1时,比电容为338 F·g^-1,当扫速达到2 000 mV·s^-1,电容保持率达到46%;在两电极体系中,0.5 A·g^-1时的比电容达到216 F·g^-1,10 000次循环后电容保持率为87%。以上性能可归结于：量子点提供了更多的离子吸附位点,且纳米片尺寸减小,缩短了离子传输路径。     

Synthesis and characterization of La1+xSr2−xCoMnO7−δ (x=0,0.2; δ=0,1)

The n=2 Ruddlesden-Popper phases LaSr₂CoMnO₇ and La_1.2Sr_1.8CoMnO₇ have been synthesized by a sol-gel method. The O6-type phases LaSr₂CoMnO₆ and La_1.2Sr_1.8CoMnO₆ were produced by reduction of the O7 phases under a hydrogen atmosphere. The materials crystallize in the tetragonal I4/mmm space group with no evidence of long-range cation order in the neutron and electron diffraction data. Oxygen vacancies in the reduced materials are located primarily at the common apex of the double perovskite layers giving rise to square pyramidal coordination around cobalt and manganese ions. The oxidation states Co³⁺/Mn⁴⁺ and Co²⁺/Mn³⁺ predominate in the as-prepared and reduced materials, respectively. The materials are spin glasses at low temperature and the dominant magnetic interactions change from ferro- to antiferromagnetic following reduction.     

Carbon Nanotube@N‐Doped Mesoporous Carbon Composite Material for Supercapacitor Electrodes

Here, carbon nanotube@N‐doped mesoporous carbon (CNT@N‐PC) composites were synthesized by using resorcinol‐formaldehyde resin as carbon source, ionic liquids (ILs) as template, and nitrogen sources and tetraethyl orthosilicate (TEOS) as assistant agent. The use of ILs‐modified CNT with nitrogen and TEOS facilitated the generation of a richer mesoporous structure. The obtained CNT@N‐PC was composed of a CNT core and mesoporous carbon particles around it. CNT@N‐PC showed a 3D network structure like “dewy cobwebs” and had a high surface area of 857 m² g^?1, uniform pore size distribution (3.0 nm), and suitable N content (4.9 at.%). When used as supercapacitor electrode, the CNT@N‐PC exhibited a high specific capacitance (244 F g^?1 at 1 A g^?1), good rate capability and favorable capacitance retention (92.5 % capacitive retention after 5000 cycles), demonstrating the potential for application in high‐performance supercapacitors.     

新型超大容量电容器电极材料—纳米水合MnO2的研究

本文用KMnO4氧化MnSO4制得纳米水合MnO2粉末,以该粉末作为活性物质制成电极,分别在物质的量浓度为0．1mol.L^-1的Na2SO4.0.5mol.L^-1的NaSO4,2.0ml.L^-1的（NH4）2SO4水溶液中,在0．0－0．85V（SCE）电位范围内用循环伏安考察电极的电容性能,循环伏安结果表明该材料在0．5mol.L^-1Na2So4水溶液中表现了良好的电容性能;用恒流充放电测得其比容量可达177．5F.g^-1.经5000次循环,电极容量保持90％以上。     

Hybrid Structures of Sisal Fiber Derived Interconnected Carbon Nanosheets/MoS2/Polyaniline as Advanced Electrode Materials in Lithium-Ion Batteries

In this work, we designed and successfully synthesized an interconnected carbon nanosheet/MoS₂/polyaniline hybrid (ICN/MoS₂/PANI) by combining the hydrothermal method and in situ chemical oxidative polymerization. The as-synthesized ICNs/MoS₂/PANI hybrid showed a “caramel treat-like” architecture in which the sisal fiber derived ICNs were used as hosts to grow “follower-like” MoS₂ nanostructures, and the PANI film was controllably grown on the surface of ICNs and MoS₂. As a LIBs anode material, the ICN/MoS₂/PANI electrode possesses excellent cycling performance, superior rate capability, and high reversible capacity. The reversible capacity retains 583 mA h/g after 400 cycles at a high current density of 2 A/g. The standout electrochemical performance of the ICN/MoS₂/PANI electrode can be attributed to the synergistic effects of ICNs, MoS₂ nanostructures, and PANI. The ICN framework can buffer the volume change of MoS₂, facilitate electron transfer, and supply more lithium inset sites. The MoS₂ nanostructures provide superior rate capability and reversible capacity, and the PANI coating can further buffer the volume change and facilitate electron transfer.     

碳螺旋纤维/MnO2复合材料的电化学性能

利用电泳沉积法(EPD)制备碳螺旋纤维基MnO_2@CMC复合材料,采用电子扫描电镜、拉曼光谱(Raman)、X射线光电子能谱(XPS)对其形貌和结构进行表征并测试其电容性能,结果显示:当电位差扫描速率为5 m V·s-1时,充放电容量较高,可达115F·g-1,在0.2 A·g-1的扫描电流下,循环200圈后电容量为96.7 F·g-1,为起始电容量的89.5%,表现出良好的电容保持率和循环稳定性。     

GO/ZIF-67模板制备rGO/NiCo2S4及高性能不对称超级电容器

以氧化石墨烯(GO)为基底,在GO表面原位生长ZIF-67并作为模板,经硝酸镍刻蚀、碳化、水热硫化制得rGO/NiCo_2S_4复合材料。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)表征复合材料的结构与形貌。随后将rGO/NiCo_2S_4复合材料制成正极材料,测试其电化学性能,测试结果显示:rGO/NiCo_2S_4-1.5 h电极材料在1 A·g~(-1)的电流密度下,其比电容值高达1 577 F·g~(-1),当电流密度达到10 A·g~(-1)时,倍率性能为86.4%,在10 A·g~(-1)的电流密度下循环2 000次后,电容保持率为76.9%。另外,在6 mol·L-1KOH电解液中,由AC//rGO/NiCo_2S_4-1.5 h组成的不对称电容器在功率密度为723 W·kg~(-1)时,能量密度为33 Wh·kg~(-1);在高功率密度为7 277 W·kg~(-1)时,能量密度仍保持为23 Wh·kg~(-1)。     

糖蜜基多孔碳球电极材料的制备及应用

以工业制糖的副产物糖蜜为新型碳源,替代传统多孔碳生产原料,制备出性能优异的多孔碳球超级电容器电极材料;探索了制备方法,优化了反应条件.利用全功能表面吸附仪、扫描电子显微镜及电化学方法对材料的结构、形貌和电化学性能进行了表征.结果表明,制得的多孔碳球比表面积高达2547 m~2/g,且展现出优异的双电层电容性(170.5 F/g).本研究可解决制糖企业对糖蜜无法大规模利用的问题,并为多孔碳的制备寻求新方法.     

溶胶-凝胶法可控制备氧化锡纳米晶包覆碳纳米管

采用溶胶-凝胶法制备了氧化锡纳米晶包覆的碳纳米管。自由Sn4+离子从稳定的Sn柠檬酸配合物中缓慢释放出来,迁移到碳纳米管上,并在碳纳米管上沉积形成了SnO2纳米晶,沉积过程完全为异相成核方式,在碳纳米管外并没有发现单独的SnO2纳米晶。这种溶胶-凝胶方法还可以用来制备无氯离子污染的、低团聚的纯SnO2纳米晶。     

氯化锌活化对炭气凝胶微球的结构与电化学性能的影响

对炭气凝胶微球在高温下进行氯化锌活化改性,并用于制作超级电容器的电极。采用扫描电镜、N2物理吸附-脱附等对炭气凝胶微球的形貌结构进行表征,采用循环伏安、恒流充放电等测定了材料的电化学性能。结果表明,氯化锌活化有效地改善了炭气凝胶微球的孔结构,通过增加炭气凝胶微球的微孔面积和体积,提高了材料的比表面积和孔隙率。经过氯化锌活化,炭气凝胶微球的电化学性能也随之得到提高,电阻明显减小,比电容提高了2倍以上。     

Responsive Ag@NiCo2O4 Nanowires Anchored on N-Doped Carbon Cloth as Array Electrodes for Nonenzymatic Glucose Sensing

The development of responsive materials in a predictable manner is high on the list of the material industry’s trends. In this work, responsive Ag@NiCo₂O₄ nanowires were, firstly, anchored on N-doped carbon cloth (NC) and, then, employed as array electrodes for a nonenzymatic glucose-sensing application. The results showed that the highly conductive NiCo₂O₄ nanowires supported Ag nanoparticles and exhibited high conductivity and electrocatalytic properties. The fully exposed crystalline planes of Ag nanoparticles provided more active surface sites. As a result, the assembled Ag@NiCo₂O₄-NC electrodes for the glucose-sensing evaluation delivered a selectivity of 2803 μA mM⁻¹ cm⁻² and a detection limit of 1.065 μM, which outperformed the literature-reported Ag- and NiCo₂O₄-based glucose-sensing catalysts.