氢氧化镍/还原氧化石墨烯复合物的超级电容性能

采用共沉淀法制备了氢氧化镍/还原氧化石墨烯复合材料,并以此为电极研究了其超级电容性能。实验发现,六方氢氧化镍纳米片被成功插入到还原氧化石墨烯的层间,这有效抑制了还原氧化石墨烯和氢氧化镍的团聚,提高了电极的稳定性。当氢氧化镍和还原氧化石墨烯的质量比为5.5∶1时,显示了最佳的电化学性能:在-0.1~0.37V的电位窗口,1A/g的电流密度下,比电容高达1 036F/g;4A/g的电流密度下快速循环3 000次后,仍然保持70%的比电容。     

Graphene-based Li-ion hybrid supercapacitors with ultrahigh performance

There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 （LTO） composite anode （G-LTO） and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries （energy source） and supercapacitors （power source）. Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA-h.g-1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·1h·g-1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0-2.5 V vs. Li/Li＋; these are among the highest values for LTO-based nano- composites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg-1 at a rate of 0.4 C （2.5 h） over a wide voltage range （0-3 V）, and still retained an energy density of 32 Wh·kg-1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.     

High-performance asymmetric supercapacitors based on reduced graphene oxide/polyaniline composite electrodes with sandwich-like structure

The sandwich-like structure of reduced graphene oxide/polyaniline(RGO/PANI) hybrid electrode was prepared by electrochemical deposition. Both the voltage windows and electrolytes for electrochemical deposition of PANI and RGO were optimized. In the composites, PANI nanofibers were anchored on the surface of the RGO sheets, which avoids the re-stacking of neighboring sheets. The RGO/PANI composite electrode shows a high specific capacitance of 466 F/g at 2 m A/cm~2 than that of previously reported RGO/PANI composites. Asymmetric flexible supercapacitors applying RGO/PANI as positive electrode and carbon fiber cloth as negative electrode can be cycled reversibly in the high-voltage region of 0–1.6 V and displays intriguing performance with a maximum specific capacitance of 35.5 m F cm~(-2). Also, it delivers a high energy density of 45.5 m W h cm~(-2) at power density of 1250 m W cm~(-2). Furthermore, the asymmetric device exhibits an excellent long cycle life with 97.6% initial capacitance retention after 5000 cycles.Such composite electrode has a great potential for applications in flexible electronics, roll-up display,and wearable devices.     

NiS2/三维多孔石墨烯复合材料作为超级电容器电极材料的电化学性能

选用合适的软模板,通过简便的一步溶剂热法成功制备了NiS₂/三维多孔石墨烯（3D rGO）复合材料。利用FESEM、TEM、XPS和电化学工作站对样品的表面形貌、元素价态和电化学性能进行表征。结果表明:制备的NiS₂/3D rGO复合材料存在石墨烯三维堆叠的孔道结构,且具备较大的比表面积,为57.51 m2g-1。电化学测试表明,在1 Ag-1的电流密度下NiS₂/3D rGO复合材料的比电容高达1 116.7 Fg-1,而且当电流密度增加到5 Ag-1时NiS₂/3D rGO复合材料的比电容为832.2 Fg-1,比电容保持率为1 Ag-1时的74.5%。在4 Ag-1电流密度下,经过1 000次循环后,NiS₂/3D rGO复合材料的比电容仍能保持91.2%。因此,NiS₂/3D rGO复合材料可作为一种理想的超级电容器电极材料。      

石墨烯在锂离子电池和超级电容器中的应用展望

由于独特的结构和优异的性质,石墨烯在锂离子电池和超级电容器领域展现出潜在的应用前景,受到了科学界和产业界的广泛关注,涌现出大量的研究工作。就石墨烯在储能领域的应用进行了分析、同时对未来发展趋势进行了预判,以期加强对石墨烯结构-性能关系的理解。首先就石墨烯在锂离子电池的正极和负极中的应用,以及石墨烯在双电层电容器和赝电容电容器中的应用进行了介绍,其次,针对石墨烯应用于双电层电容器中存在的挑战进行了论述,同时针对性地提出了应用于双电层电容器的石墨烯结构。最后,提出了实现石墨烯基双电层电容器的商业化应用的"三步走路线"。     

氧化石墨烯-SiO2杂化材料对环氧树脂拉伸性能的影响

为了提高环氧树脂的力学性能,采用一步合成法制备得到氧化石墨烯(GO)-SiO₂(GO-SiO₂)杂化材料,利用扫描电子显微镜(SEM)对杂化材料的形貌进行表征,成功制得了具有三维结构的GO-SiO₂杂化材料;将GO、SiO₂颗粒和GO-SiO₂以相同的含量(质量分数均为0.1%)添加到环氧树脂中制备复合材料,利用万能强力仪测试复合材料的拉伸性能,比较3种填料对树脂基复合材料拉伸性能的影响;再分别将质量分数为0.1%、0.3%和0.5%的GO-SiO₂添加到环氧树脂中制备GO-SiO₂/环氧树脂复合材料,比较不同质量分数的GO-SiO₂对树脂基复合材料拉伸性能的影响;利用SEM对拉伸样条的断截面进行扫描测试,分析了不同种类和不同比例的填料对树脂基复合材料的增强增韧效果,并分析其增强增韧机制。结果表明: GO-SiO₂的增强增韧效果明显优于GO和SiO₂颗粒,当GO-SiO₂的添加质量分数为0.3%时,其增强增韧效果最佳。     

石墨烯季戊四醇相变复合材料导热性能的分子动力学研究

低导热是限制储能材料实际应用的一大缺点,具有极高导热系数的石墨烯可作为导热填料有效改善储能材料的导热性能。本文通过反向非平衡分子动力学的方法,借助Materials Studio软件,模拟研究了石墨烯(GE)质量分数为0.5%、1%、1.5%、2%、2.5%、3%的石墨烯/季戊四醇(GE/PE)固-固相变复合材料的导热性能和内部相互作用。结果表明:石墨烯的添加可有效提升季戊四醇的导热性能,随着GE质量分数的增加,GE/PE复合相变材料的导热率、界面热导以及相互作用能均逐渐增大,且趋势幅度相一致,材料整体导热系数的增加归因于石墨烯结构的变化。本文可为石墨烯改善季戊四醇导热性的实验研究提供指导。     

石墨烯负载花球状二氧化锰复合材料制备及其电容性能研究

利用高锰酸钾与乙醇之间的氧化还原反应,在多孔石墨烯表面沉积纳米二氧化锰花球,获得了一种新型的复合电极材料。通过XRD,TG,SEM,TEM等分析手段确定了材料的晶体结构、化学成分、微观形貌特征。电化学性能测试表明:纳米二氧化锰花球具有优异的比电容,但是倍率性能和循环性能不足。通过在石墨烯表面负载纳米二氧化锰花球,能够显著增加石墨烯的比电容,同时改善纳米二氧化锰花球的倍率性能和循环性能。采用0.5mol/L K_2SO_4电解液,进行三电极循环伏安测试,复合电极材料在2mV·s^-1扫速下的比电容高达295F·g^-1,在1000mV·s^-1扫速下,比电容仍然可达102F·g^-1,同时100mV·s^-1,1000次循环后,电容循环保持率可达96.3%。这表明石墨烯负载花球状二氧化锰材料是一种极具潜力的超级电容器电极材料。     

超级电容器复合材料MnO2/活性炭的研究

采用化学共沉淀法制备了α-MnO2*nH2O和活性炭的复合电极材料,对其结构和形貌分别用XRD和SEM进行了表征.循环伏安、交流阻抗以及恒流充放电等测试结果表明复合电极材料比α-MnO2*nH2O或活性炭电极具有更好的电化学可逆性和理想的电化学电容行为.随活性物质量增加,复合电极的比电容量增长率趋于稳定.     

沉淀转化法制备的纳米Ni(OH)2-C复合材料的结构和电化学性能

研究了用沉淀转化法、通过掺钴和纳米炭材料制备的Ni(OH)2-C和Ni0.96Co0.04(OH)2-C纳米复合材料的结构和电化学性能．Ni(OH)2-C和Ni0.96Co0.04(OH)2-C都是β-Ni(OH)2晶体结构．Ni(OH)2电化学性能主要与其晶体粒径、晶体结构和导电性有关．掺入纳米导电炭黑,可以改善Ni(OH)2的电化学性能．掺入纺锤形颗粒的SPC比片状颗粒HGC炭黑较明显改善Ni(OH)2的电化学性能．掺入高比表面积活性炭,不能改善Ni(OH)2电化学性能．掺杂Co可以提高倍率放电能力和可逆性．掺杂Co和炭的Ni0．96Co0．04(OH)2-C复合材料,具有高比容量.     

Aqueous-phase synthesis of Ag-TiO2-reduced graphene oxide and Pt-TiO2-reduced graphene oxide hybrid nanostructures and their catalytic properties

We demonstrate an aqueous solution method for the synthesis of a Ag-TiO₂-reduced graphene oxide (rGO) hybrid nanostructure (NS) in which the Ag and TiO₂ particles are well dispersed on the rGO sheet. The Ag-TiO₂-rGO NS was then used as a template to synthesize Pt-TiO₂-rGO NS. The resulting hybrid NSs were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), and catalytic studies. It was found that TiO₂-rGO, Ag-TiO₂-rGO and Pt-TiO₂-rGO NSs all show catalytic activity for the reduction of p-nitrophenol to p-aminophenol by NaBH₄, and that Pt-TiO₂-rGO NS exhibits the highest catalytic activity as well as excellent stability and easy recyclability.      

Preparation of carbon-coated iron oxide nanoparticles dispersed on graphene sheets and applications as advanced anode materials for lithium-ion batteries

We report a novel chemical vapor deposition （CVD） based strategy to synthesize carbon-coated Fe203 nanoparticles dispersed on graphene sheets （Fe2Og@C@G）. Graphene sheets with high surface area and aspect ratio are chosen as space restrictor to prevent the sintering and aggregation of nanoparticles during high temperature treatments （800 ℃）. In the resulting nanocomposite, each individual Fe2O3 nanoparticle （5 to 20 nm in diameter） is uniformly coated with a continuous and thin （two to five layers） graphitic carbon shell. Further, the core-shell nanoparticles are evenly distributed on graphene sheets. When used as anode materials for lithium ion batteries, the conductive-additive-free Fe2OB@C@G electrode shows outstanding Li＋ storage properties with large reversible specific capacity （864 mAh/g after 100 cycles）, excellent cyclic stability （120% retention after 100 cycles at 100 mA/g）, high Coulombic efficiency （-99%）, and good rate capability.     

Continuous wafer-scale graphene on cubic-SiC（O01）

The atomic and electronic structure of graphene synthesized on commercially available cubic-SiC（001）/Si（001） wafers have been studied by low energy electron microscopy （LEEM）, scanning tunneling microscopy （STM）, low energy electron diffraction （LEED）, and angle resolved photoelectron spectroscopy （ARPES）. LEEM and STM data prove the wafer-scale continuity and uniform thickness of the graphene overlayer on SIC（001）. LEEM, STM and ARPES studies reveal that the graphene overlayer on SIC（001） consists of only a few monolayers with physical properties of quasi-freestanding graphene. Atomically resolved STM and micro-LEED data show that the top graphene layer consists of nanometer-sized domains with four different lattice orientations connected through the 〈110〉-directed boundaries. ARPES studies reveal the typical electron spectrum of graphene with the Dirac points close to the Fermi level. Thus, the use of technologically relevant SiC（001）/Si（001） wafers for graphene fabrication repre-sents a realistic way of bridging the gap between the outstanding properties of graphene and their applications.     

3D graphene/fly ash waste material for hybrid supercapacitor electrode: specific capacitance analysis

The performance of supercapacitor energy storage is depending on the type of the material that is used as supercapacitor electrode. Graphene has been widely used as the base material for a lot of applications due to its remarkable properties. In this research, we try to combine 3D Graphene with waste material fly ash to be used as the electrode of supercapacitor. Fly ash is a residual material from burning pulverized coal in electric generation power plants which contain metal oxide materials such as iron oxide and aluminum oxide. This residual material might be usable as an electrode for supercapacitor due to its material contained. As the base material, the 3D graphene was successfully fabricated by using low pressure chemical vapor deposition (LPCVD) method and afterwards the fly ash was coated on the top of 3D graphene. The chemical properties and surface structure of the electrode material was studied by using Raman spectroscopy and field emission scanning electron spectroscopy (FESEM). 3 electrode systems were used to analyze the cyclic voltammetry results. According to the results, they show that the highest specific capacitance of 3D graphene/fly ash (FA) was about 0.025 F/cm2 at the lowest scan rate of 5 mV/s and it is recommended to use as the supercapacitor electrode.     

Flexible and transparent electrothermal film heaters based on graphene materials

High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 °C, which shows transmittance of over 80% at 550 nm, can reach a saturated temperature of up to 42 °C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 °C can exhibit high steady-state temperatures of 150 and 206 °C under an applied voltage of 60 V with a maximum heating rate of over 7 °C s(-1) . For flexible heating films patterned on polyimide, a steady-state temperature of 72 °C could be reached in less than 10 s with a maximum heating rate exceeding 16 °C s(-1) at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices.     

基于沉淀转化法制备的纳米NiO混合电容器研究

运用沉淀转化法制备Ni(OH)2超微粉末,并通过热处理得到纳米NiO.利用TG、XRD、TEM、N2吸附,循环伏安和恒流充放电测试对样品进行了分析和表征.结果表明,实验制备的NiO粒径为10nm左右,比表面积达到186.3m2/g,并具有合适的孔径分布,NiO赝电容器的工作电压为0.35V,在电流密度为60mA/g时,其比容达到243F/g.以NiO和中孔活性炭分别作为正极和负极材料组装成NiO-AC混合电容器,混合电容器的工作电压达到1.5V,其能量密度为NiO赝电容器的17.2倍,并具有更好的功率特性.     

锐钛矿/TiO2（B）复合纳米线制备及其锂存储研究

以锐钛矿TiO2粉末为原料,通过碱液水热反应并辅以酸洗和热处理工艺,制备出一致性良好的锐钛矿/TiO2（B）一维复合纳米线材料。研究结果表明该复合纳米线在30mA/g（0.1C）充放电速率下,该锐钛矿/TiO2（B）一维壳核结构材料100圈循环后容量高达196mAh/g;在4500mA/g（15C）充放电速率下,充放电容量达到125mAh/g。由于其优良的电化学性能,该一维复合结构材料有望成为下一代最有前途的锂离子电池电极材料。     

基于化学气相沉积石墨烯/PEDOT-PSS共混复合材料的导电薄膜

采用液相剥离技术制备基于化学气相沉积（CVD）石墨烯/聚乙撑二氧噻吩-聚苯乙烯磺酸（PEDOT-PSS）共混复合材料的导电薄膜。采用原子力显微镜和SEM表征石墨烯/PEDOT-PSS复合薄膜的微观结构;通过紫外吸收谱、X射线光电子能谱、FTIR等分析技术探索该共混复合薄膜的导电机制。结果表明：石墨烯/PEDOT-PSS导电薄膜具有优异的电学特性,其方阻约为8 Ω/□;表面分析表明,石墨烯与PEDOT主链中五元噻吩发生π-π共轭效应,由此引起两作用体之间电子云密度的变化,该变化增加了PEDOT主链的载流子离域化程度,有利于PEDOT导电性的提升,同时提高石墨烯的载流子浓度,使CVD石墨烯/PEDOT-PSS复合薄膜的导电能力增强。     

有源式超级电容器-蓄电池混合储能系统的研究

建立了基于功率变换器的有源式超级电容器-蓄电池混合储能系统的模型,并对控制环节进行了设计,提出了一种在脉动负载下蓄电池恒流输出的控制策略.对该模型进行了实验,并与无源式储能结构的性能进行了比较,结果表明,有源式混合储能系统配置灵活,能够大大提升系统的性能和优化蓄电池的工作过程,非常适合于负载动率脉动,尤其是瞬时功率很高,但平均功率较低的应用场合.最后,给出了确定有源式混合储能系统中超级电容器技术参数和容量配置的依据.     

3D打印石墨烯制备技术及其在储能领域的应用研究进展

石墨烯优异的力学和物理性能使其成为理想的储能材料。因结构精确可控,易实现规模化制备,3D打印石墨烯材料有望在储能领域得到广泛应用。本文全面综述了3D打印石墨烯制备技术及其在储能领域的应用研究进展。石墨烯墨水的黏度和可打印性是实现石墨烯3D打印的制约因素。实现工艺简单、浓度可控、无黏结剂石墨烯墨水的规模化打印将成为3D打印石墨烯制备技术未来的研究热点。石墨烯超级电容器、锂硫电池、锂离子电池等储能元件一体化打印成型是3D打印石墨烯在储能领域应用的发展方向。