石英晶体微天平分析不同介孔二氧化锰材料的电化学性能

以碳酸锰(MnCO3)为前体,空气氛围下采用不同温度(300℃、350℃、400℃)煅烧, 制备了3种介孔二氧化锰(MnO2)材料,分别与粘结剂混合喷涂至石英晶片作为电极,利用石英晶体微天平(QCM)监测了3种材料在0.1 mol/L Na2SO4溶液中随循环伏安过程的电化学性能变化.分析结果表明,3种材料在首圈循环中都呈现出显著的质量增加,发生了不可逆反应过程; 300℃煅烧制备的MnO2材料具备更好的电化学稳定性和容量保持能力.将300℃, 350℃和400℃煅烧的MnO2各自作为正极与活性炭负极组成超级电容器, 进行充放电测试,首圈均有35％～40％的容量损失; 三者稳定循环时放电容量分别为15.9, 12.9和11.7 mA h/g.QCM的分析与充放电测试结果相一致,表明QCM可用于比较不同介孔二氧化锰材料的电化学性能.     

静电纺丝法制备煤基纳米碳纤维及其在超级电容器中的应用

以氧化处理的新疆库车原煤、聚丙烯腈(PAN)和N,N-二甲基甲酰胺(DMF)为原料,通过静电纺丝法制备了直径均匀的煤基纳米碳纤维前驱体,经高温碳化、CO2活化得到煤基超级电容器电极材料.使用X射线能谱仪、物理吸附仪、扫描电子显微镜、红外光谱仪和热分析仪等对前驱体及产物进行了表征.结果表明,原煤经过高锰酸钾氧化处理后,部分连接大分子的烷基链被打断,含氧基团明显增多,使原煤在DMF中的溶解度大幅提高.电化学测试结果表明,在电流密度为1 A/g时,煤基活化碳纤维的比电容为259.7F/g,在1000次循环充放电后比电容仍然保持99.2%.     

静电纺纳米纤维基超级电容器无粘合剂电极材料的研究进展

对高性能超级电容器不断增长的需求促进了无粘合剂电极材料的快速发展。静电纺纳米纤维由于具有良好的柔性、大比表面积、高孔隙率、容易制备等优点引起了研究者们的强烈关注。本文综述了静电纺纳米纤维基无粘合剂电极材料在超级电容器领域的研究进展,阐述了不同材料的设计制备过程和提升电化学性能的诸多方法,并指明了静电纺纳米纤维基超级电容器无粘合剂电极材料的发展机遇与挑战,为性能优异的无粘合剂超级电容器电极材料的进一步开发与应用拓宽了思路。     

用于超级电容器的锰钴氧化物/碳纤维材料

The development of high-performance supercapacitor electrode materials is imperative to alleviate the ongoing energy crisis. Numerous transition metals (oxides) have been studied as electrode materials for supercapacitors owing to their low cost, environmental-friendliness, and excellent electrochemical performance. Among the developed binary transition metal oxides, manganese cobalt oxides typically show high theoretical capacitance and stable electrochemical performance, and are widely used in the electrode materials of supercapacitors. However, the poor conductivity and active material utilization of manganese cobalt oxide-based electrode materials limit their potential capacitance application. Cotton is mainly composed of organic carbon-containing materials, which can be transformed to carbon fibers after calcination. The resultant carbonaceous material exhibits a large specific surface area and good conductivity. Such advantages could potentially suppress the negative effects caused by the poor conductivity and small specific surface area of manganese cobalt oxides, thereby improving the electrochemical performance. Herein, we firstly deposited manganese cobalt oxides on cotton by a simple hydrothermal method, yielding a composite of manganese cobalt oxides and carbon fibers via subsequent calcination, to improve the electrochemical performance of the electrode material. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), and electrochemical characterizations were used to investigate the physical, chemical, and electrochemical properties of the prepared samples. The fabricated manganese cobalt oxides in the composite were uniformly dispersed on the carbon fiber surface, which increased the contact between the interface of the electrode material and electrolyte, and enhanced electrode material utilization. The electrode material was confirmed to have well contacted with the electrolyte during a contact angle test. Hence, a pseudo-capacitance reaction completely occurred on the manganese cobalt oxide material. Moreover, the addition of carbon fibers reduced the resistance of the material, resulting in excellent capacitive performance. The capacitance of the prepared composite was 854 F∙g^-1 at a current density of 2 A∙g^-1. The capacitance was maintained at 72.3% after 2000 cycles at a current density of 2 A∙g^-1. These results indicate that the manganese cobalt oxide and carbon fiber composite is a promising electrode material for high-performance supercapacitors. The findings presented herein provide a strategy for coupling with carbon materials to enhance the performance of supercapacitor electrode materials based on manganese cobalt oxides. Thus, novel insights into the design of high-performance supercapacitors for energy management are provided.     

The effect of ultrasonic and HNO3 treatment of activated carbon from fruit stones on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors

The effect of ultrasonic treatment and modification with nitric acid of activated carbon obtained from fruit stones, on the parameters of electric double-layer (EDL) as well as on farad–volt characteristics of its boundary with electrolyte 7.6 m KОН, 4 m KI and 2 m ZnI₂ aqueous solutions has been studied by means of precision porometry, cyclic voltamperometry, electrochemical impedance spectroscopy and computer simulation methods. It is shown that HNO₃ treatment results in an increase of the electrostatic capacitance up to 202 F/g in 7.6 m KОН-solution as well as pseudocapacitance up to 1250 F/g in 4 m KI. This increase is supposed to be related both with hydrophilicity and with an increase of the density of states on Fermi level. The ultrasonic treatment enables one to significantly increase (more than 200 times) the density of states on Fermi level which in turn causes both quantitative and qualitative changes in farad–volt dependences. A hybrid supercapacitor with specific capacitance of 1100 F/g and specific energy of 49 Wh/kg per active mass of two electrodes was developed.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂）,制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射（XRD）,热重分析（TGA）对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构;MnO₂纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极,活性炭（AC）为负极,1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器,发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g^-1,且表现出良好的电容特性和大电流放电性能.     

基于碳纳米管的柔性平面微型超级电容器

超薄电子器件的蓬勃发展和日益增长的人性化需求极大促进了可穿戴柔性微器件的发展,但是沉积电极材料在柔性基板上的技术仍处于起步阶段. 本文通过结合四面体制备器辅助涂层法和激光切割叉指构型技术,大规模地将碳纳米管沉积到商用印刷纸上作为电极,切割组装获得了柔性对称微型超级电容器. 制得的微型超级电容器的电化学性能可以通过简单地选择不同的四面体制备器模型制备不同厚度的碳纳米管薄膜进行调控. 优化获得的碳纳米管薄膜基微型超级电容器在0.02 mA的电流下,具有高达4.56 mF/cm²的面电容. 微型超级电容器经过连续10000次循环,器件的性能仍然可以保持接近100%. 四面体制备器辅助涂层方法和激光切割叉指构型技术为制备经济的微电子器件提供了新的视角. 附着碳纳米管的纸电极实现了可调控的面电容,在未来制备平面构型的不对称微超级电容器方面展示了广阔的应用前景.     

Synergistic effect of Cr2O3 and Co3O4 nanocomposite electrode for high performance supercapacitor applications

The fabrication of high performance supercapacitor electrodes has been greatly investigated for future high power storage applications. In this present work, chromium oxide-cobalt oxide based nanocomposite (Cr₂O₃–Co₃O₄ NC) was synthesized using the hydrothermal approach. Moreover, the cyclic voltammetry (CV) study reveals the Cr₂O₃–Co₃O₄ NC delivers a high specific capacitance of 619.4 F/g at 10 mV/s. The electrochemical impedance spectra (EIS) of Cr₂O₃–Co₃O₄ NC possess the solution resistance (R_s) and charge transfer resistance (R_ct) of 0.68 Ω and 0.03 Ω respectively. The Galvanostatic charge-discharge (GCD) analysis demonstrated the prolonged charge-discharge time and good rate capability of the Cr₂O₃–Co₃O₄ NC. The cyclic stability of Cr₂O₃–Co₃O₄ NC delivers superior capacitive retention of 83% even after 2000 cycles. The asymmetric supercapacitor (ASC) device based on Cr₂O₃–Co₃O₄//AC yielded an energy density of 4.3 Wh/kg at the corresponding power density of 200 W/kg. Furthermore, the ASC delivers superior cyclic stability of 74.8% even after 1000 consecutive charge-discharge cycles.     

水性聚苯胺纳米线超级电容器电极材料

使用"假高稀"方法,分别以过硫酸铵、硝酸铁和三氯化铁为氧化剂,含有1个乙氧基基团的酸性磷酸酯为质子酸,经过原位聚合制备了直径分别为78～90 nm、18～30 nm和16～25 nm水分散性聚苯胺纳米线.聚苯胺膜的电导率分别为18,32和35 S cm-1,比表面积为65,70和82 m2g-1.该聚苯胺纳米线能够很好地分散在水中,是一种环境友好型超级电容器电极材料.该电极材料在1 mol L-1四乙基氟硼酸/碳酸丙烯酯非水性电解液中,在-1～1 V扫描范围内,以0.4 A g-1的放电速率下,分别得到了110,140和152 F g-1的比容,比电容与材料的比表面积和电导率有关,随着比表面积以及电导率的增大而增大.聚苯胺纳米线电极材料有较高的充放电效率(大于98%),表明了它们有很好的电化学可逆性.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂）,制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射（XRD）,热重分析（TGA）对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构;MnO₂纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极,活性炭（AC）为负极,1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器,发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g^-1,且表现出良好的电容特性和大电流放电性能.