石墨烯/聚吡咯复合电极材料超电容性能研究进展

分析了目前石墨烯和聚吡咯(PPy)用作电极材料的不足,详细介绍了近年来超级电容器用石墨烯/PPy复合电极材料的研究进展,指出石墨烯/PPy复合材料在能量转换和存储领域的未来发展方向.     

微撞击流反应器制备镍钴复合氢氧化物超级电容器材料及其性能研究

镍基复合超级电容器电极材料如镍钴复合氢氧化物,由于其比电容大、循环性能好等优点受到了电化学界的广泛关注。相比于纯Ni(OH)₂,镍钴复合氢氧化物材料由于过渡金属元素之间的协同作用,其电化学性能一般会更佳。但是镍钴复合氢氧化物材料的性能与其颗粒内部的组分分布均匀性有很大关联,而组分分布又依赖于沉淀反应时反应器内的微观混合均匀程度。将微观混合性能优良的微撞击流反应器（MISR）应用于镍钴复合氢氧化物材料的共沉淀制备,结果表明MISR能够显著改善镍钴复合氢氧化物材料的颗粒粒径、尺寸分布、团聚程度以及电化学性能：三电极体系测试下,所制备材料的初始比电容为1548.0 F/g,1000圈充放电循环后电容保持率为106.0%;二电极体系测试下,器件的初始比电容为30.6 F/g,1000圈循环后电容保持率为75.6%。     

微撞击流反应器制备镍钴复合氢氧化物超级电容器材料及其性能研究

镍基复合超级电容器电极材料如镍钴复合氢氧化物,由于其比电容大、循环性能好等优点受到了电化学界的广泛关注。相比于纯Ni(OH)₂,镍钴复合氢氧化物材料由于过渡金属元素之间的协同作用,其电化学性能一般会更佳。但是镍钴复合氢氧化物材料的性能与其颗粒内部的组分分布均匀性有很大关联,而组分分布又依赖于沉淀反应时反应器内的微观混合均匀程度。将微观混合性能优良的微撞击流反应器（MISR）应用于镍钴复合氢氧化物材料的共沉淀制备,结果表明MISR能够显著改善镍钴复合氢氧化物材料的颗粒粒径、尺寸分布、团聚程度以及电化学性能：三电极体系测试下,所制备材料的初始比电容为1548.0 F/g,1000圈充放电循环后电容保持率为106.0%;二电极体系测试下,器件的初始比电容为30.6 F/g,1000圈循环后电容保持率为75.6%。     

Preparation and characterization of graphene and Ni-decorated graphene using flower petals as the precursor material

A simple method is reported for preparing graphene and nickel-decorated graphene from the petals of lotus and hibiscus flowers by heating the original petals and petals soaked in a nickel(II) chloride solution ranging 800–1600 °C under a flowing argon atmosphere for 0.5 h. The products have been characterized by scanning and transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Graphene prepared at high temperature (>1200 °C) is purer than that obtained at a lower temperature (800 °C). The presence of nickel has been found to have improved the quality of the graphene and electron density near the Fermi energy level.     

氧化石墨烯的酸性还原及其超级电容性能

采用改进的Hummers法制备氧化石墨烯(GO),在酸性条件(pH=5)下以180°C进行水热还原,通过调节水热反应时间来制备不同还原程度的还原氧化石墨烯(RGO)。研究了不同的水热反应时间对RGO结构及超级电容性能的影响。结果表明：控制水热反应时间可以制备出还原程度不同的RGO,在电化学测试中,随着水热反应时间的延长,RGO电极的比电容呈先上升后下降的趋势。当水热反应时间为6 h时,RGO电极表现出最佳的超级电容性能,其在1 A/g电流密度下比电容达到251 F/g,相对于GO电极提高了225%。经过500次充放电循环后,RGO-6电极比电容保持率达到92%,具有优异的循环稳定性。     

Nanostructured manganese dioxides: Synthesis and properties as supercapacitor electrode materials

Low-cost layered manganese oxides with the rancieite structural type were prepared by reduction of KMnO₄ or NaMnO₄ in acidic aqueous medium, followed or not by successive proton- and alkali-ion-exchange reactions. Samples were characterized by X-ray diffraction, energy dispersive X-ray analysis, BET surface area measurements, thermal analyses and X-ray photoelectron spectroscopy. As a result of successive exchange steps, compounds with high surface area (reaching 200 m² g⁻¹) can be obtained, and in the case of syntheses made with KMnO_4, the α-MnO₂ phase is formed. Capacitive properties of the synthesized materials were studied using potentiodynamic cycling in K₂SO₄. Correlations between the electrochemical and the physicochemical properties of the samples were investigated. The interesting conclusion is that the morphology and the size of the particles influence directly the capacitance, and that among the samples presenting the best morphology, the compounds derived from K-containing rancieite-type compounds (and containing α-MnO₂) present a better cycleability.     

氮掺杂石墨烯/多孔碳复合材料的制备及其氧还原催化性能

采用简单、无模板的方法制备了氮掺杂多孔石墨烯/碳复合材料(NPGC)。采用SEM、XRD、Raman、XPS等分析手段对NPGC的形貌、组成以及结构进行了表征，利用旋转圆盘电极技术测试了其电催化氧还原反应(ORR)活性。结果表明，葡萄糖在水热后生成的碳与石墨烯成功复合，并在950℃炭化、活化后形成了相互渗透、结构良好的三维片状多孔网络结构；其氮含量高达9.47%。NPGC作为一种高效的非金属ORR电催化剂，在碱性溶液中具有较高的起始电位[0.87 V(vs RHE)]和较大的极限电流密度(4.7 mA?cm^?2)，以及其ORR平均转移电子数为3.8。与商业Pt/C催化剂相比，NPGC具有较强的耐甲醇性和长期耐久性，且制备成本较低，具有广阔的应用前景。     

Synthesis of graphene/vitamin C template-controlled polyaniline nanotubes composite for high performance supercapacitor electrode

A graphene nanosheet/polyaniline nanotube (GPNT) composite is prepared for the first time by in-situ chemical oxidative polymerization of aniline using vitamin C as a structure directing agent. The vitamin C molecules lead to the synthesis of polyaniline (PANI) nanotubes through the development of rod-like assembly by H-bonding in an aqueous medium. The initially synthesized graphene oxide/polyaniline nanotubes composite is reduced to graphene using hydrazine monohydrate followed by re-oxidation and protonation of the PANI to produce the GPNT nanocomposite. This novel composite showed a high specific capacitance of 534.37 F/g and an excellent energy density of 74.27 Wh/kg at a constant current of 0.5 mA. Besides, the GPNT composite exhibited excellent cycle life with 91.4% specific capacitance retained after 500 charge-discharge cycles. The excellent performance is due to the synergistic combination of graphene which provides good electrical conductivity and mechanical stability, and PANI nanofiber which deals with good redox activity.     

Fe_3O_4/石墨烯复合材料的制备及其电化学性能研究

以FeCl_3·6H_2O和FeCl_2·4H_2O为铁源,以Na OH溶液为沉淀剂,选择共沉淀法制备Fe_3O_4∕石墨烯复合物。以Fe~(2+)和Fe~(3+)的浓度作为变量制得5种不同比例的Fe_3O_4/石墨烯纳米复合材料,然后将所得复合材料压制成电极片,组装成超级电容器后进行循环伏安(CV)、恒电流充放电(GCD)、交流阻抗(EIS)测试,探究Fe_3O_4与石墨烯的含量比对复合材料电化学性能的影响。结果表明,当FeCl_3·4H_2O和FeCl_2·4H_2O用量分别为0.456 g和0.665 g,氧化石墨烯用量为150 mg时,所制备复合材料的电化学性能最佳,比电容可达510 F/g。     

Fe_3O_4/石墨烯复合材料的制备及其电化学性能研究

以FeCl_3·6H_2O和FeCl_2·4H_2O为铁源,以Na OH溶液为沉淀剂,选择共沉淀法制备Fe_3O_4∕石墨烯复合物。以Fe⁽²⁺⁾和Fe(2+)和Fe⁽³⁺⁾的浓度作为变量制得5种不同比例的Fe_3O_4/石墨烯纳米复合材料,然后将所得复合材料压制成电极片,组装成超级电容器后进行循环伏安(CV)、恒电流充放电(GCD)、交流阻抗(EIS)测试,探究Fe_3O_4与石墨烯的含量比对复合材料电化学性能的影响。结果表明,当FeCl_3·4H_2O和FeCl_2·4H_2O用量分别为0.456 g和0.665 g,氧化石墨烯用量为150 mg时,所制备复合材料的电化学性能最佳,比电容可达510 F/g。     

氮掺杂微孔活性炭制备及其超级电容性能

以土豆为碳源,乙二胺为氮源,氢氧化钾为活化剂制备具有微孔结构高比表面积氮掺杂活性炭。通过N_2物理吸附、扫描电镜、透射电镜、拉曼光谱和元素分析研究活性炭比表面积、孔结构、形貌及元素组成,并测试其电化学性能。结果表明,当碱碳质量比为5∶1时(NC600-800-5),活性炭材料比表面积最高2 440 m~2·g~(-1)、孔容最大1.07 cm~3·g~(-1)、孔径最大0.82 nm和1.80 nm。电流密度1 A·g~(-1)时比电容可达370 F·g~(-1),经3 000次循环充放电后,比电容保持率为95.2%。     

Synthesis of Mn3O4/N-doped graphene hybrid and its improved electrochemical performance for lithium-ion batteries

Mn₃O₄/N-doped graphene (Mn₃O₄/NG) hybrids were synthesized by a simple one-pot hydrothermal process. The scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray powder diffraction (XRD), Thermogravimetric analysis (TG), Raman Spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize the microstructure, crystallinity and compositions. It is demonstrated that Mn₃O₄ nanoparticles are high-dispersely anchored onto the individual graphene nanosheets, and also found that, in contrast with pure Mn₃O₄ obtained without graphene added, the introduction of graphene effectively restricts the growth of Mn₃O₄ nanoparticles. Simultaneously, the anchored well-dispersed Mn₃O₄ nanoparticles also play a role as spacers in preventing the restacking of graphene sheets and producing abundant nanoscale porous channels. Hence, it is well anticipated that the accessibility and reactivity of electrolyte molecules with Mn₃O₄/NG electrode are highly improved during the electrochemical process. As the anode material for lithium ion batteries, the Mn₃O₄/NG hybrid electrode displays an outstanding reversible capacity of 1208.4 mAh g⁻¹ after 150 cycles at a current density of 88 mA g⁻¹, even still retained 284 mAh g⁻¹ at a high current density of 4400 mA g⁻¹ after 10 cycles, indicating the superior capacity retention, which is better than those of bare Mn₃O₄, and most other Mn₃O₄/C hybrids in reported literatures. Finally, the superior performance can be ascribed to the uniformly distribution of ultrafine Mn₃O₄ nanoparticles, successful nitrogen doping of graphene and favorable structures of the composites.     

Synthesis of polypyrrole-reduced graphene oxide composites by in-situ photopolymerization and its application as a supercapacitor electrode

A highly conductive polypyrrole (PPy)-reduced graphene oxide (RGO) composite with an electrical conductivity of 610 S m⁻¹ was successfully synthesized by the in-situ photopolymerization of pyrrole in a graphene oxide suspension. Graphene oxide (GO) played the role of an electron acceptor and was reduced as it accepted electrons. The reduction of GO was confirmed by the increase in the C/O ratio of RGO with the UV irradiation time as well as the high electrical conductivity of PPy-RGO composite. Through the thermogravimetric analysis, it has been found that the PPy-RGO composite exhibited high thermal stability compared to the GO and PPy. This material was used as an electrode in a supercapacitor cell and showed excellent performance for electrical energy storage. The composite exhibited a specific capacitance of 376 F g⁻¹ at a scan rate of 25 mV s⁻¹.     

Synthesis of nanocast ordered mesoporous carbons and their application as electrode materials for supercapacitor

Various nanocast ordered mesoporous carbons (OMCs) were synthesized using mesoporous silicas such as SBA-15, SBA-16, KIT-6, SBA-3 and MCM-48 as templates via nanocasting pathway. The structures of OMCs were analyzed by X-ray diffraction, transmission electron microscope and nitrogen sorption technique. These OMCs with well-defined pore structure were used as model electrode materials for investigating the influence of pore structure on their double layer capacitances. The cyclic voltammetry and galvanostatic charge/discharge measurements were conducted to estimate the capacitive behaviour of OMCs. The results show that the mesopore structures of OMCs play an important role in improving surface utilization for the formation of electrical double layer. OMCs synthesized from SBA-15 and SBA-16 show great advantage over others because their micropores are being easy accessible through the mesopores, thus allowing rapid electrolyte ion diffusion. To achieve a higher specific capacitance (μF cm⁻²), the optimized amount ratio between micropore and mesopore needs to be controlled. In addition, great impact of the electrode disc thickness on the capacitive performance was demonstrated by a series of careful measurements.     

夹心型生物碳电极材料的制备及超级电容器性能

选择板栗壳为碳源(CC),炭化后用KOH活化,制得CC700-OH电极材料.通过SEM、TEM、XRD以及BET等对其形貌和性能进行了表征与测试,发现CC700-OH具有孔/片穿插的夹心结构.在电流密度为1 A/g时,比电容为540 F/g,在电流密度为10 A/g下,循环6000圈后比电容仍可保持初始值的98％.在二...     

石墨烯/δ-MnO2复合材料的制备及其超级电容器性能

采用螯合法制备了RGO/δ-MnO₂复合材料,并用X射线粉末衍射（XRD）、低压氮气吸附脱附（BET）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、能谱（EDS）、热重（TGA）对其结构和物相进行表征。采用循环伏安测试（CV）、恒电流充放电（GCD）以及循环测试对所制材料电化学储能进行测试。结果表明RGO/δ-MnO₂复合材料比纯石墨烯和纯δ-MnO₂具有更优异的电化学性能。当电流密度为1 A·g^-1时,RGO/δ-MnO₂复合材料的比电容可达322.6 F·g^-1,比纯δ-MnO₂电极材料高234.2 F·g^-1,比纯石墨烯高212.1 F·g^-1。当电流密度放大10倍后,RGO/δ-MnO₂复合材料的比电容保留率为79.1%。在1000次恒流充放电测试后,比电容为252 F·g^-1（99.6%）,说明该方法制备的RGO/δ-MnO₂复合材料是一种有应用前景的超级电容器电极材料。     

Fabrication of a sulfonated aramid‐graphene nanoplatelet composite paper and its performance as a supercapacitor electrode

Sulfonated aramid (SA) fiber modified graphene nanoplatelet (GnP) paper was fabricated employing simple vacuum filtration technique. The SA macromolecules were noncovalently attached on the surface of GnP through π?π interactions. Robustness of the film was characterized via dynamic mechanical analysis study. X‐ray photoelectron spectroscopy was employed to investigate the extent of surface functionalization. The specific capacitance of 166 F/g was obtained for the sulfonated graphene nanoplatelet composite paper with 97% of specific capacitance retained after 1000 cycles establishing the cyclic stability of the said composite paper. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45099.     

High performance of a solid-state flexible asymmetric supercapacitor based on graphene films

Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO(2)-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H(2)SO(4) electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg(-1)) and power density (6.8 kW g(-1)), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g(-1) with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability.