微波加热与传统加热制备高比表面活性炭的对比研究

以中间相炭微球为原料,KOH为活化剂,采用微波加热与传统加热2种方法在不同条件下制备出高比表面积活性炭.研究表明:活性炭比表面积和孔容随着KOH/MCMB的增大先增大后减小,采用微波加热制得的活性炭具有较高的比表面积,KOH/MCMB较小时,比表面积和孔容随活化时间的延长达到最大值后不再发生变化,在KOH/MCMB较大时,比表面积和孔容随活化时间的延长先增大后减小,采用微波加热可大大缩短活化时间,通过FTIR分析,微波加热比传统加热所制得的活性炭具有较低浓度的含氧基团.     

载镍活性炭材料及复合型超级电容器

为提高碳基电化学电容器的比电容和和能量密度,采用化学沉积法将少量镍氧化物沉积在活性炭上,得到沉积镍氧化物的活性炭材料并以此材料做成复合电极用于混合型电化学电容器的正极.研究显示,沉积镍氧化物后,碳材料的比表面积略有减小,但孔径分布没有明显变化.复合电极作为混合型电容器的正极时,比电容达到194.01F/g,比纯活性炭正极的175F/g提高了10.84%;复合电极在6mol/L的电解液中析氧电势为0.296V,比纯活性炭电极的0.220V高出0.076V,因此,具有较高的能量密度.不同放电电流密度下的恒电流测试结果显示,沉积镍氧化物活性炭复合电极的比电容值没有明显变化,与纯活性炭电极一样表现出良好的功率特性.采用沉积镍氧化物活性炭作为正极材料的复合型电容器,在6mol/L的KOH水溶液作为电解液时,单体电容器的工作电压可以达到1.2V,高于纯活性炭制备的双层型电容器0.2V.充放电循环10000次时,复合型电容器的电容仅降低到初始电容的90%.上述结果表明,在活性炭上沉积少量镍氧化物颗粒可以提高碳基电化学电容器的比电容和能量密度.     

微波法制备活性炭及去除水中双酚A的研究

以核桃壳为原料,氯化锌和碳酸钾为活化剂,微波加热为能源制备活性炭。研究了微波功率、微波作用时间、剂料比对制备活性炭的产率及吸附性能影响。最佳工艺条件为干核桃壳:氯化锌:碳酸钾(质量比)为1∶1∶1,微波功率600 W,活化时间7 min。在该条件下制得的活性炭碘值为1 073.8 mg/g,测得该活性炭比表面积为1 003.8 m2/g,孔结构以1～10 nm孔径为主。活性炭对双酚A的吸附符合Freundlich吸附等温规律。     

氢氧化镍超级电容器的性能研究

采用化学沉淀法制备Ni(OH)_2,组装的氢氧化镍超级电容器在0.1A/g的电流密度下,首次放电比电容为206.6F/g,等效串联电阻为25.6Ω,能量密度为9.97W·h/kg。由于Ni(OH)_2的氧化还原反应进行得充分彻底,所以等效串联电阻小,比电容和能量密度均高于活性炭超级电容器。复合超级电容器的各项储能性能均介于两者之间。当电流密度增大到0.6A/g时,活性炭超级电容器被击穿,而复合超级电容器和氢氧化镍超级电容器在1A/g时的比电容仍然高于160F/g,倍率性能较好。     

不同活化方式制备碳电极材料的电化学性能

以碳化后的中间相沥青为原料,分别采用化学活化和物理-化学联合活化工艺制备了超级电容器用活性炭电极材料,对不同活化方式制备的活性炭电极材料的微晶结构、孔径分布、比电容量、循环伏安和交流阻抗特性进行了比较。实验结果表明：采用物理-化学联合活化工艺制备的活性炭电极材料具有更理想的微晶结构和中孔含量。活性炭电极材料的结构与孔隙分布对电性能有明显影响,采用联合活化方式制备的电极材料具有较高的面积比容量、较好的功率特性及较理想的电容特性。     

电极用金属活性炭的催化制备与表征

采用催化活化法制备了含有不同种类和数量金属的金属活性炭,利用氮气吸附、扫描电子显微镜、定电流充放电等方法表征了金属活性炭的结构、形貌和电化学性能,并考察了金属种类和数量对活化烧失率以及活性炭形貌、孔结构、吸附性能和电容量的影响．结果表明,金属催化活化法有利于活性炭孔隙率的提高,在1．8nm以下的微孔和3．4～4．2nm范围的中孔数量增加幅度最为明显,但对孔径分布影响不大;金属活性炭的中孔以墨水瓶状孔隙为主,不利于对较大分子吸附质的吸附,但金属活性炭具有提供双电层电容和准电容的双层功效,是制作超级电容器电极的适宜材料．     

孔结构对煤基活性炭电化学性能的影响

以煤为前驱体,KOH为活化剂制备系列煤基活性炭电极材料.采用N_2吸附法及电化学测试对活性炭的孔结构和电化学性能进行了表征,研究了孔结构对活性炭电极材料的电化学性能的影响.结果表明,采用化学活化法可制备出比表面积1 048～3 581 m~2/g、中孔率7%～91%的活性炭电极材料.在3 mol/L KOH无机电解液体系及1 mol/L(C_2H_5)_4NBF_4/碳酸丙烯酯(PC)有机电解液体系中,活性炭电极材料的比电容分别达到322 F/g,190 F/g.2～3 nm的中孔对电解质离子在电极材料中的扩散有着重要作用,可以有效降低电解液的扩散阻力,提高电极材料比表面积的利用率,从而增强电容器的电化学性能.     

物理化学两步活化法制备煤基活性炭电极材料

为提高超级电容器用的活性炭电化学性能,通过物理化学两步活化法制备煤基活性炭.以太西无烟煤为原料,通过成型和炭化后,用CO_2物理活化制得柱状活性炭(AC-1).将AC-1酸洗脱灰,并用KOH水溶液浸渍,进行第2步化学活化,制得超级电容器用的煤基活性炭(AC-2),两步活化后总收率为45.18%.将活性炭制备成电极材料,并在三电极和双层电容器体系下进行电化学性能测试.结果表明:在KOH电解液浓度为6mol/L,电流密度为0.5A/g时,三电极体系下,比电容由68.5F/g(AC-1)提高到122.5F/g(AC-2),在纽扣式超级电容器体系下,比电容由75F/g(AC-1)提高到165.5F/g(AC-2),且AC-2具有良好的长循环稳定性,经过5 000次的循环后电容量几乎无衰减.与物理活化所得活性炭相比,物理化学两步活化所得活性炭的总孔容和中孔率明显增加,其作为电极材料的电化学性能显著提高.     

响应面法优化混合活化剂制备脱硅稻壳基活性炭

对以脱硅稻壳为原料、Na OH和Na2CO3为混合活化剂制备活性炭的工艺进行了4因素(活化温度、活化时间、活化剂混合比、浸渍液质量分数)3水平的响应面优化研究.结果显示:活化温度和浸渍液质量分数对活性炭的碘吸附值有显著地影响.在活化温度635℃,活化时间35 min,混合比4∶1,浸渍液质量分数40%时碘吸附值出现极值,验证实验的碘平均值为1 383.5 mg/g,与预测值基本吻合.另外对所制活性炭进行了性能表征,采用SEM表征了活性炭的形貌,BET法计算了活性炭的比表面积,BJH方程计算出活性炭的孔径分布.得到其比表面积为1 566.1 m2/g,平均孔径为2.05 nm,总孔容为0.80 cm3/g.     

污泥活性炭的制备及其性能的优化

以高碑店污水处理厂二沉池的剩余污泥为主要原料,采用化学活化法制备污泥活性炭,通过活化剂筛选实验得出最佳的活化剂,在此基础上研究了废弃纸质材料对于污泥活性炭性能提高的影响,并对制备过程中的相关问题进行了研究.选用化学活化法将污泥制备成活性炭,通过正交设计法得到最佳制备条件为:氯化锌4 mol/L、活化温度750℃、活化时间60 min、废弃纸质材料添加比例40%,该条件下制作的活性炭比表面积为680.85 m2/g.     

Synthesis of mesoporous carbon as electrode material for supercapacitor by modified template method

The pore structures and electrochemical performances of mesoporous carbons prepared by silica sol template method as electrode material for supercapacitor were investigated. The mean pore size and mass specific capacitance of the mesoporous carbons increase with the increase of mass ratio of silica sol to carbon source （glucose）. A modified template method, combining silica sol template method and ZnCl2 chemical activation method, was proposed to improve the mass specific capacitance of the mesoporous carbon with an improved BET surface area. The correlation of rate capability and pore structure was studied by constant current discharge and electrochemical impedance spectroscopy. A commercially available microporous carbon was used for comparison. The result shows that mesoporous carbon with a larger pore size displays a higher rate capability. Mesoporous carbon synthesized by modified template method has both high mass specific capacitance and good rate capability.     

Effect of Adding Microwave Absorber on Structures and Properties of Hypercoal-Based Activated Carbons

Using lignite-based hypercoal as raw material,KOH as activator and CuO as microwave absorber,we prepared hypercoal-based activated carbons by microwave-assisted activation.The pore structure and the electrochemical performance of the activated carbons were tested,and the effects of adding CuO in the activation reaction process were also investigated.The activated carbons prepared were characterized by nitrogen adsorption-desorption,X-ray diffraction (XRD) and scanning electron microscopy (SEM).The specific surface area and mesoporous ratio of the hypercoal-based activated carbon are 1 257 m~2/g and 55.4%,respectively.When the activated carbons are used as the electrode materials,the specific capacitance reaches 309 F/g in 3 M KOH electrolyte.In comparison with those prepared without CuO absorber,the specific capacitance increases by 11.6%.It was proved that the addition of microwave absorber in microwave-assisted activation was a low-cost method for rapidly preparing activated carbon,and it could effectively promote the development of the pore structure and improve its electrochemical performance.     

Comparison of capacitive behavior of activated carbons with different pore structures in aqueous and nonaqueous systems

The pore structures of two activated carbons from sawdust with KOH activation and coconut-shell with steam activation for supercapacitor were analyzed by N2 adsorption method. The electrochemical properties of both activated carbons in 6 mol/L KOH solution and 1 mol/L EtgNPF4/PC were compared, and the effect of pore structure on the capacitance was investigated by cyclic voltammetry, AC impedance and charge-discharge measurements. The results indicate that the capacitance mainly depends on effective surface area, but the power property mainly depends on mesoporosity. At low specific current （1 A/g）, the maximum specific Capacitances of 276.3 F/g in aqueous system and 123.9 F/g in nonaqueous system can be obtained from sawdust activated carbon with a larger surface area of 1 808 m^2/g, butat a high specific current, the specific capacitance of coconut-shell activated carbon with a higher mesoporosity of 75.1% is more excellent. Activated carbon by KOH activation is fitter for aqueous system and that by steam activation is fitter for nonaqueous system.     

Influence of KOH activation techniques on pore structure and electrochemical property of carbon electrode materials

1 INTRODUCTIONSupercapacitor is a kind of newenergy storagedevice , which can fill the gap between the conven-tional capacitor and the battery[1 ,2]. Supercapa-ciors are nowutilizedin many fields ,such as spaceindustry ,national defense ,warindustry ,electricalvehicle , wireless communication, and consume e-lectronics .It is well known that the electrode ma-terial is the key factor to determine the perform-ance of supercapacitor . At present ,the activatedcarbonis the main marketed availa…     

Adsorption of K+ from an aqueous phase onto an activated carbon used as an electric double-layer capacitor electrode

The adsorption capacity and absorption rate for electrolyte onto activated carbon are important parameters used to characterize activated carbon electric double-layer capacitor electrodes. In this paper the pore structure of typical commercial activated carbons, and various Mn-doped activated carbons prepared on a laboratory scale, are described. The pore structure was characterized by N2 adsorption/desorption isotherms. Isotherms for K+ adsorption onto these activated carbons from the aqueous phase were also obtained. The experimental, equilibrium K+ adsorption data were fitted to the Langmuir, Freundlich or Temkin equations. Adsorption of K+ onto the activated carbons was measured and plotted as a function of time. The adsorption kinetic data were modeled by either pseudo-first or pseudo-second order equations. The Elvoich equation, a liquid film diffusion and an intra-particle diffusion model were used to fit the kinetic data. The results indicate that the adsorption of K+ onto activated carbon is influenced by many factors including pore size distribution, specific surface area and the surface chemistry of the activated carbons. The Temkin equation best describes the equilibrium adsorption data. The pseudo-second order model exactly describes the whole adsorption process, which is controlled by both liquid film and intra-particle diffusion.     

High-performance porous carbon for supercapacitors prepared by one-step pyrolysis of PF/gelatin blends

A high-performance porous carbon material for supercapacitor electrodes was prepared by using a polymer blend method. Phenol-formaldehyde resin and gelatin were used as carbon precursor polymer and pore former polymer, respectively. The blends were carbonized at 800 °C in nitrogen. SEM, BET measurement and BJH method reveal that the obtained carbon possesses a mesoporous characteristic, with the average pore size between 3.0 nm and 5.0 nm. The electrochemical properties of supercapacitor using these carbons as electrode material were investigated by cyclic voltammetry and constant current charge-discharge. The results indicate that the composition of blended polymers has a strong effect on the specific capacitance. When the mass ratio of PF to gelatin is kept at 1:1, the largest surface area of 222 m²/g is obtained, and the specific capacitance reaches 161 F/g.     

含油污泥制备高比表面积活性炭

以含油污泥为原料,氢氧化钠为活化剂,在氮气保护下,通过室内静态热解炉制备高比表面积活性炭。研究炭化温度、活化升温方式、活化温度、活化时间和碱碳质量比m(NaOH)／m(C)对高比表面活性炭的影响。采用全自动比表面与孔隙度分析仪、钨灯丝环境扫描电子显微镜等测试设备,分别对产品的比表面积与孔径分布、组成及微观形貌进行定性或定量分析。研究结果表明,含油污泥制备高比表面积活性炭的较佳条件为:炭化温度500℃,活化升温方式(c),活化温度800℃,活化时间1h, m(NaOH)／m(C)=2。采用本方法制备的活性炭比表面积大于2000m2/g,平均孔径小于2nm,总孔容大于2cm3/g,性能优于普通活性炭,可作为能源储存介质、电极材料、高效吸附剂的基础材料,为含油污泥的资源化利用提供了一条新途径。     

应用模板法从煤沥青制备中孔活性炭

以煤沥青为原料,应用纳米二氧化硅模板法制备中孔活性炭,并考察焦模比、碱碳比以及活化温度对活性炭孔结构和收率的影响。结果表明,所得活性炭试样孔径分布最大值与模板剂孔径尺寸相吻合。在焦模比为2∶1、碱碳比为4.5∶1、活化温度为850℃时,所制活性炭总比表面积为1729 m^2/g,其中中孔比表面积为1702 m^2/g,占总比表面积的98.43%。