石墨烯基复合超级电容器材料研究进展

石墨烯基复合材料因其优异的性能广泛应用于各个领域,尤其在超级电容器的研究中。本文对石墨烯基复合超级电容器材料的结构进行了分类,并分别从石墨烯-碳基复合材料、石墨烯-导电高分子复合材料、石墨烯-过渡金属化合物复合材料的角度,总结了不同石墨烯基复合超级电容器材料的研究进展,重点强调了优化电极结构和提高电极性能之间的关系。同时,概述了石墨烯基复合材料在锂离子电池、太阳能电池、催化等其他方面的应用。获得高能量密度、功率密度以及长循环寿命的超级电容器是其作为电极材料的发展趋势。

Preparation and electrochemical characterization of C/PANI composite electrode materials

Taking the nano-sized carbon black and aniline monomer as precursor and （NH4）2S2O6 as oxidant, the well coated C/polyaniline（C/PANI） composite materials were prepared by in situ polymerization of the aniline on the surface of well-dispersed nano-sized carbon black for supercapacitor. The micro-structure of the C/PANI composite electrode materials were analyzed by SEM. The electrochemical properties of C/ PANI and PANI composite electrode were characterized by means of the galvanostatic charge-discharge experiment, cyclic voltammetric measurement and impedance spectroscopy analysis. The results show that by adding the nano-sized carbon black in the process of chemical polymerization of the aniline, the polyaniline can be in situ polymerized and well-coated onto the carbon black particles, which may effectively improve the aggregation of particles and the electrolyte penetration. What’s more , the maximum of specific capacitance of C/PANI electrode 437.6F·g -1 can be attained. Compared with PANI electrode, C/PANI electrode shows more desired capacitance characteristics, smaller internal resistance and better cycle performance.

Nickel Sulfide/Graphene/Carbon Nanotube Composites as Electrode Material for the Supercapacitor Application in the Sea Flashing Signal System

This work presents NiS/graphene/carbon nanotube （NiS/GNS/CNT） composites as electrode material for the supercapacitor application in sea flashing signal systems. NiS nanosheets were closely anchored on the conductive GNS-CNT networks. As a result, the NiS/GNS/CNT electrode showed a high specific capacitance of 2 377 F.g^-1 at 2 mV.s^-1 and good cycling stability compared with the pure NiS （1 599F.g^-1）. The enhanced electrochemical performances are attributed to the synergetic effect between the conductive carbon and the pseudo-capacitive NiS. The high performance supercapacitor may provide application in the sea flashing signal system.

One-step strategy to graphene/Ni（OH）2 composite hy- drogels 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.

Coherent Mn3O4-carbon nanocomposites with enhanced energy-storage capacitance

Nanostructured Mn3O4 was introduced to activated C （AC） by a novel sonochemical reaction, and the resulting nanocomposites were examined as supercapacitor electrodes. The sonication not only catalyzed the redox reaction but also promoted the diffusion of the precursors, causing the formation of coherent nanocomposites with Mn3O4 nanoparticles grown and uniformly distributed inside the mesopores of the AC. In addition, the extreme local condition in the sonochemical synthesis yielded an excessive amount of divalent manganese ions and oxygen vacancies. This novel microstructure endowed the sample with a superior performance, including a specific capacitance of 150 F/g compared with the value of 93 F/g for AC at a charge/discharge rate of 100 mA/g. A Li-ion capacitor delivered an energy density of 68 Wh/kg, compared with 41 Wh/kg for the AC capacitor at a power density of 210 W/kg.

Fabrication of hybrid Co_3O_4/NiCo_2O_4 nanosheets sandwiched by nanoneedles for high-performance supercapacitors using a novel electrochemical ion exchange

Electrochemical ion exchange has been used to tailor the composition of transition metal oxides （Co3O4） electrode with enhanced capacity while maintaining its crystal structure and morphology. Specifically, Ni ions were incorporated to C03O4 nanosheets sandwiched by nanoneedles to form Co3O4/NiCo2O4 composite. As positive electrode for supercapacitors, the Co3O4/NiCo2O4 composite presents a high areal capacitance of 3.2 F cm^-2 （1060 F g^-1） at a current density of 5 mA cm^-2 and outstanding rate capability as well as long cycle stability. Moreover, the assembled aqueous asymmetric supercapacitor based on Co3O4/NiCo2O4//carbon cloth electrodes delivers a considerable energy density of 3.0 mW hcm^-3 at power density of 136 mW cm^-3, and high rate capability （85% retention at a current density of 30 mA cm^-2）. A safety light composed of ten green LEDs in parallel was lit for -360 s using two identical supercapacitors in series, indicating a promising practical application.