复合黏结剂制备CDI电极及其脱盐性能研究

电容去离子(CDI)是一种低能耗、环保的含盐水脱盐技术。电极对CDI系统的脱盐起着决定性作用。黏结剂对电极的性能有很大的影响，进而影响CDI脱盐性能。研究选用聚四氟乙烯(PTFE)和聚偏氟乙烯(PVDF)作为复合黏结剂，利用涂覆法制备活性炭电极，讨论其应用于CDI的可能性。采用流变、接触角、电阻率、SEM、BET、电化学测试等方法对电极性能进行表征，使用自制的脱盐装置，研究复合电极的脱盐性能。结果表明：涂覆电极呈现亲水性，具有较好的稳定性，50次循环伏安后比电容仅下降7.35%，最大比电容可达141.78 F·g^-1。随着PTFE的增加，电极亲水性、导电性以及强度略有下降，电极的稳定性略有上升。脱盐结果显示，PTFE/PVDF配比为5∶5时，电极具有良好的脱盐性能，脱盐量达到8.567 mg·g^-1。     

改性活性炭/碳纳米管复合电极脱盐性能研究

采用改性CNT*作为CDI电极导电剂,制备AC*/CNT*复合电极,考察其脱盐性能。利用BET、FTIR和TEM对AC或CNT的表面结构、官能团种类和分散性进行分析。利用电化学工作站和SEM对复合电极的比电容、阻抗和表面形貌进行分析。结果表明,通过改性,AC*的比表面积达到672.48 m2/g,增加了29.43%;CNT*的比表面积为117.39 m2/g,下降了9.94%,但其分散性得到有效改善。根据循环伏安测试和静态脱盐实验结果 ,按AC*∶CNT*∶PVDF=7.2∶0.8∶2质量比制备的电极效果最好,比电容高达130.48 F/g,比吸附量达到7.29 mg/g。     

改性活性炭/碳纳米管复合电极脱盐性能研究

采用改性CNT*作为CDI电极导电剂,制备AC*/CNT*复合电极,考察其脱盐性能。利用BET、FTIR和TEM对AC或CNT的表面结构、官能团种类和分散性进行分析。利用电化学工作站和SEM对复合电极的比电容、阻抗和表面形貌进行分析。结果表明,通过改性,AC*的比表面积达到672.48 m2/g,增加了29.43%;CNT*的比表面积为117.39 m2/g,下降了9.94%,但其分散性得到有效改善。根据循环伏安测试和静态脱盐实验结果 ,按AC*∶CNT*∶PVDF=7.2∶0.8∶2质量比制备的电极效果最好,比电容高达130.48 F/g,比吸附量达到7.29 mg/g。     

电容法脱盐工艺条件优化与脱盐性能比较

以石墨带为电极材料,研究了工作电压、进料流量和隔网厚度等工艺条件对电容法脱盐（CDI）性能的影响。结果表明：工作电压由0.8 V增加至2.0 V时,脱盐率和质量比吸附量先增加然后趋于稳定;进料流量由48 mL/min增加至238 mL/min时,脱盐率和质量比吸附量先增加后减小;隔网厚度由0增加至1.8 mm时,质量比吸附量先减小后增加。在电压1.6 V、进料流量142 mL/min、隔网厚度1.8 mm时,CDI脱盐性能较好。在上述相同的工艺条件下,对CDI与膜电容法脱盐（MCDI）进行了对比研究。结果表明：在第1个循环的吸附阶段,MCDI脱盐率和电流效率分别比CDI增加了31.68%和36.16%;16 h循环吸脱附实验后,MCDI再生率为99.01%。表明MCDI比CDI具有更好的脱盐性能和再生性能。     

PPy/CS复合电极热压成型条件的优化

以壳聚糖（CS）和聚吡咯（PPy）制备的复合材料为活性基体,在不添加黏结剂的条件下,采用热压成型法制备复合电极。重点考察了不同导电剂对电极力学性能的影响,热压温度、成型压力、热压时间及不同种类活性炭对电极电化学性能的影响规律。结果表明：通过热压法不添加黏结剂能够获得性能优良的复合电极;以活性炭为导电剂的电极溶胀性和亲水性最好,且活性炭的比表面积越大电极的电化学性能越好;电极热压成型的最优条件为：热压温度150℃、成型压力10 MPa、热压时间20 min。     

PPy/CS复合电极热压成型条件的优化

以壳聚糖(CS)和聚吡咯(PPy)制备的复合材料为活性基体,在不添加黏结剂的条件下,采用热压成型法制备复合电极。重点考察了不同导电剂对电极力学性能的影响,热压温度、成型压力、热压时间及不同种类活性炭对电极电化学性能的影响规律。结果表明:通过热压法不添加黏结剂能够获得性能优良的复合电极;以活性炭为导电剂的电极溶胀性和亲水性最好,且活性炭的比表面积越大电极的电化学性能越好;电极热压成型的最优条件为:热压温度150℃、成型压力10 MPa、热压时间20 min。     

高硫石油焦分级多孔炭的制备及电容脱盐性能研究

电容脱盐是基于双电层原理的新兴脱盐技术,由于其具有所需电压低、能量消耗小和无二次污染等优点受到研究学者的广泛关注。多孔炭具有较高的比表面积、孔结构可调、物理和化学性质稳定等优点,常被用于电容脱盐的电极材料。多孔炭中非炭材料的引入,能为材料提供一定的赝电容,提高材料的电容脱盐性能。本文探究了含硫多孔炭对电容脱盐的影响,实验以高硫石油焦为炭前驱体,KOH为活化剂,在高温下一步活化得到分级多孔炭,并对多孔炭的电容脱盐性能进行了测定。结果表明,高硫石油焦KOH活化后,孔体积和比表面积得到很大的提高,而硫含量随着KOH添加量的增加逐渐降低直至为零。通过分级多孔炭电容脱盐的测试,发现微孔不利于电容脱盐,介孔更利于电容脱盐。与不含硫官能团的ACs进行对比,含硫官能团对脱盐具有增益效果,AC-2电极单循环脱盐量达到5.00 mg/g,单位比表面积的脱盐量达到0.015 mg/m~2。     

电容去离子技术的电极材料研究进展

电容去离子(CDI)是一种装置结构简单、无二次污染、能耗低的新型水处理技术，被应用在海水淡化、苦咸水脱盐和废水处理等方面。文章分析了CDI的工作原理，从电极材料的比表面积、导电性能和盐吸附容量等方面综述了基于双电层理论的碳质材料和基于法拉第反应的赝电容材料，阐述了不同电极材料在掺杂和改性等操作修饰后对脱盐性能的影响，为当前研究提供理论基础和研究思路。     

气相吸附用成型活性炭

椰壳渣等制备的粉状高比表面积活性炭加入酚醛树脂黏结剂成型后,经二次碳化、活化后制成气相吸附用成型活性炭.主要研究了黏结剂添加量和二次活化温度对成型活性炭抗压强度、堆积密度、油气吸附性能的影响,从而确定了最佳黏结剂添加量为30%,最佳二次活化温度为800℃.     

神木煤制中低温热解用型煤工艺参数优化研究

为制备中低温热解用型煤,以我国典型低阶烟煤神木煤为原煤,以煤焦油重质组分及沥青为黏结剂,研究成型压力、水分、黏结剂种类及添加量对型煤冷热强度的影响,考察复合黏结剂配比对型煤冷热强度的影响规律。结果表明:型煤的强度随着压力和水分的增加呈先增大后减小的趋势;黏结剂种类对型煤强度的影响作用不同,煤焦油和煤沥青添加量的增加分别增强了冷强度和热强度;在成型水分13%、成型压力141 MPa、煤焦油重质组分质量分数9%和煤沥青质量分数为16%的优化工艺条件下,型煤的冷、热强度均较优,可以满足中低温热解直立炭化炉对原料的要求。     

石墨毡电极与集流体的简单可靠粘接及其在电解中的应用

石墨毡有比表面积大、导电性强、廉价易得等优点,被认为是极具应用前景的三维电极材料。为使电极与集流体良好接触,采用高导电碳黑做导电填料、聚偏氟乙烯做粘接剂制备了导电胶,实现了对石墨毡电极与柔性石墨纸集流体的简单可靠粘接。探究了导电胶配比、涂胶量和固化压力条件对石墨毡-集流体粘接试样导电性能和粘结强度的影响。粘接试样的接触电阻相较于靠压紧的无胶试样降低了50%,拉伸剪切强度达到与石墨毡自身强度接近的25.3×10^-3 MPa。将胶粘石墨毡电极用于印刷电路板酸性氯化铜蚀刻液的电解再生和铜回收,单槽电压降低了0.08 V。这使得以金属铜计的电解再生和铜回收的比能耗降低了80 kW·h·t^-1。     

Improved performance of iron-chromium flow batteries using SnO2-coated graphite felt electrodes

Polyacrylonitrile-based graphite felt has the properties of high temperature resistance, corrosion resistance, low thermal conductivity, large surface area and excellent electrical conductivity. It has become the preferred material for flow battery electrodes, but its chemical activity is poor. In order to improve the electrochemical activity of graphite felt electrodes, the electrodes were prepared by SnO₂-coated graphite felt. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to analyze the microscopic morphology of SnO₂-coated graphite felt electrodes. Electrochemical impedance spectroscopy, cyclic voltammetry and charge-discharge tests were performed using an electrochemical workstation to investigate the electrocatalytic activity of SnO₂-coated graphite felt electrodes and their cell performance. The results show that the SnO₂ coating on the graphite felt surface forms a convex and concave microstructure, which further increases the specific surface area of the electrode, and at the same time successfully introduces oxygen-containing functional groups to the electrode surface, increasing the electrochemically active spots on the surface. In addition, the presence of oxygen defects in the SnO₂ crystal structure provides more electrochemically active sites and improves the electrochemical performance of the graphite felt electrode. At a current density of 142 mA cm^?2, the charge-discharge capacity of the battery assembled with the SnO₂-coated graphite felt electrode was significantly improved; when the current density was 250 mAcm^?2, the Coulombic efficiency of the electrode (TGF-2) coated with a concentration of 0.1 M could reach 84%.     

聚合物功能性填料豆秸基活性炭的制备及导电性能研究

为了增强橡胶制品的耐热性或者一般高分子聚合物的导电性,活性炭作为一种功能性填料被用于相关材料的成型加工中。本文采用豆秸活化,并在高温下炭化制备了高分子材料的填料—活性炭。并且通过多种测试手段分析其电化学性能。本文主要研究了采用KOH直接活化豆秸粉的方法,并通过700℃高温碳化获得高比表面积豆秸基活性炭。通过改变原料与KOH的混合比例,得到不同的产品。通过电化学性能测试、氮气吸附测试、电镜分析等对所得到的碳材料进一步表征。结果显示,采用改变KOH的比例制得的不同碳材料都含有丰富的微孔及一定量的介孔和大孔。其中DFC-1:1.5样品的总比表面积达到1269 m2/g,微孔率达93.8%。将所制备的碳材料制备成电极材料,在浓度为30%氢氧化钾电解液中进行电化学性能测试。测试表明,活性炭表现出良好的超电容特性。其中DFC-1:1.5电化学性能较好,在电流密度0.1 A/g下,其电容值达到255.1F/g,在电流密度增加到5A/g时其比电容依然可达160.7 F/g。通过三电极交流阻抗测试,碳材料的内阻非常小,说明导电性能良好。     

Synthesis of nitrogen doped microporous carbons prepared by activation-free method and their high electrochemical performance

Nitrogen-doped microporous carbons (N-MCs) were prepared by the carbonization of the polyvinylidene fluoride (PVDF)/melamine mixture without chemical activation. The electrochemical performance of the N-MCs was investigated as a function of PVDF/melamine ratio. It was found that, without additional activation, the N-MCs had a high specific surface area (greater than 560 m²/g) because of the micropore formation by the release of fluorine groups. In addition, although the specific surface area decreased, nitrogen groups were increased with increasing melamine content, leading to an enhanced electrochemical performance. Indeed, the N-MCs showed a better electrochemical performance than that of microporous carbons (MCs) prepared by PVDF alone, and the highest specific capacitance (310 F/g) was obtained at a current density of 0.5 A/g, as compared to a value of 248 F/g for MCs. These results indicate that the microporous features of N-MC lead to feasible ion transfer during charge/discharge duration and the presence of nitrogen groups as strong electron donor on the N-MC electrode in electrolyte could provide a pseudocapacitance by the redox reaction.     

表面积对煤基电容炭电化学性能的影响

以河北无烟煤为原料,KOH为活化剂,采用化学活化法制备具有高比表面积的煤基电容炭,考察煤基电容炭的比表面积对无机/有机体系下双电层电容器电化学性能的影响。结果表明:随着碱煤比的增加,所制电容炭的比表面积、总孔容和中孔率增加。当碱煤比达到3.5时,所制电容炭的比表面积、总孔容和中孔率分别为3 389 m2/g、2.041 cm3/g、49.9%。可以看出,对于无机/有机体系,在相同的比表面积变化规律下,电容器电化学性能的变化规律略有不同。当碱煤比小于2时,所制电容炭的比表面积小于2 400 m2/g,此时对于无机/有机体系,电容器的比电容变化规律相同,比电容都随比表面积的增大增幅明显。当碱煤比大于2时,所制电容炭的比表面积大于2 400 m2/g,此时随着比表面积的继续增大,对无机体系,电极材料的比电容几乎维持不变,比电容最高可达331 F/g;对有机体系,电极材料的比电容增幅减缓,比电容最高可达192 F/g。当碱煤比为2时,电容炭的比表面积为2 382 m2/g,此时无论对于无机体系还是有机体系,电容器在保持相对较高比电容的同时具有相对较高的电容保持率。由此可知,一定程度上,提高电极材料的比表面积有利于提升超级电容器的电化学性能。制备具有适宜比表面积的电容炭,在得到较高电容性能电容器的同时更能有效控制成本。同时,以煤为原料制备电容炭,可提升煤的附加值,具有很好的市场前景。     

Enhanced capacitive deionization of graphene/mesoporous carbon composites

Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g(-1) for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g(-1)). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.     

Characteristics of Nitric Acid‐Modified Carbon Nanotubes and Desalination Performance in Capacitive Deionization

Multiwalled carbon nanotubes (MWCNTs) were treated by nitric acid to probe the effect of nitric acid modification on their properties and desalination performance in capacitive deionization (CDI). The nitric acid modification exerts a slight influence on the morphologies, specific surface area, and pore properties of the MWCNTs but can increase the amount of oxygen‐containing functional groups and then obviously enhance the specific capacitance of the electrodes. Thus, the desalination efficiency can be significantly improved as the modified MWCNTs serve as electrodes in CDI. The adsorption of salt ions on the original and modified MWCNT electrode is fitted well by the Freundlich isotherm other than the Langmuir isotherm.     

Hydrous RuO(2)-Carbon Nanofiber electrodes with high mass and electrode-specific capacitance for efficient energy storage

We demonstrate a new strategy for the fabrication of supercapacitor electrodes possessing high mass and area-specific capacitance for efficient charge storage, which can be extremely useful for the development of light, compact and high performance supercapacitors for a variety of high power demanding applications. High mass and electrode area specific capacitances were attained by using Hydrous Ruthenium Oxide (HRO)-Carbon Nanofiber (CNF) hybrid electrodes prepared by the deposition of HRO (~31% Ru content) on both the outer and inner surfaces of a cylindrical hollow CNF having open tips. Electrochemical studies of the uniformly deposited HRO nanoparticles on the CNF surface showed a mass specific capacitance of 645 F g(-1) and an electrode specific capacitance of 1.29 F cm(-2) with a HRO-CNF material loading of 2 mg cm(-2) in the supercapacitor electrodes. The mass specific capacitance of pure HRO is 301 F g(-1), whereas the mass specific capacitance of HRO in the HRO-CNF electrode is ~1300 F g(-1), which is very close to the theoretical capacitance of HRO. This enhanced charge storage ability, high rate capability, better cyclic stability and low ESR of the HRO-CNF will be useful for the development of high performance supercapacitors.     

Competitive effect of KOH activation on the electrochemical performances of carbon nanotubes for EDLC: Balance between porosity and conductivity

This work is focused on the competitive effects on the performance of the electric double layer capacitors (EDLCs) between porosity increase and simultaneous conductivity decrease for KOH-activated carbon nanotubes (CNTs). A series of the CNTs have been activated with KOH to enhance their surface areas for application in EDLCs. The microstructure of the activated carbon nanotubes (ACNTs) is characterized with N₂ adsorption, transmission electron microscopy (TEM) observation and electric conductivity measurement. Their electrochemical performances are evaluated in aqueous KOH electrolyte with galvanostatic charge/discharge, cyclic voltammetry, and ac impedance spectroscopy. It is found that the KOH activation enhances the specific surface area of the CNTs and its specific capacitance but decreases its electric conductivity and the rate performance in EDLC. By controlling the activation of the CNTs to balance the porosity and conductivity, ACNTs with both high capacitance and good rate performance are obtained.