【作者】 杨常玲；

【导师】 孙彦平；

【作者基本信息】 太原理工大学 ， 化学工程与技术， 2010， 博士

【摘要】 超级电容器在电子、新能源等高新技术领域具有广阔的应用。其性能主要是由电极材料决定的,因此降低材料成本,获得最佳性价比,成为电极材料研发的关键。本文通过发泡将沥青和酚醛树脂制备成具有微米级泡壁的三维网络结构,再通过炭化、水蒸气活化制备成活性泡沫炭;以糠醇为原料,通过模板法制备了孔结构分布窄的微孔模板炭;以天然鳞片石墨为原料,采用改进的Hummers法,制备了具有开放表面结构的石墨烯。用循环伏安法、恒流充放电和交流阻抗法等电化学评价方法,研究了微孔和开放平面内的充放电平衡容量和功率特性,并考察了孔结构对双电层电容性能的影响,及其与电解质离子的匹配关系。以热塑性酚醛树脂为原料,加入12 wt%的六次甲基四胺固化剂,在氮气保护下以10℃/min从室温升温到约210℃发泡,并继续升温到700℃炭化。在水流量为1.0～2.0mL/min的蒸汽中700～850℃活化60～180min,得到比表面在474～1287m2/g,孔径在0.64～5.0nm之间的酚醛基活性泡沫炭;以软化点为285℃各向同性煤焦油沥青为原料,加入30wt%甲苯,设定初始压力为3.0MPa,在300℃下发泡,经过氧化炭化,并在850℃下,水流量为1.0mL/min水蒸汽活化60～180min,得到了比表面为399～953m2/g,孔径在0.59～5.0nm之间的沥青基活性泡沫炭。比较了比表面为961m2/g的酚醛基活性泡沫炭和比表面积为953m2/g的沥青基活性泡沫炭的双电层电容性能,在1.0mA充放电时,二者容量相近,分别为117 F/g和112.5 F/g,当电流增加到50mA时,二者的容量差别变大,前者为60.5 F/g,后者为28.3 F/g,表明酚醛基比沥青基活性泡沫炭的孔容更大一些,有利于提高功率特性;比较了比表面积为1267 m2/g的酚醛基活性泡沫炭和比表面积为1297 m2/g的酚醛基活性炭纤维的双电层电容特性,在1.0mA充放电时,容量相差不大,前者为142.4 F/g,后者为169.8 F/g,随着充放电电流的增大,两种活性炭的电容量差异有所提高,在50mA时,前者为77.1 F/g,后者为121.5 F/g,表明活性泡沫炭作为电极材料虽然性能较活性炭纤维低些,但制备简单。利用NaY型分子筛,通过糠醇浸渍、聚合、700～800℃炭化、HF脱模等过程,制备了孔径在1.0nm和1.6nm附近双峰分布,比表面积约为578～826m2/g的模板炭。选用比表面积为826m2/g的模板炭,考察了在1.5mol/L的NaOH、KOH、NaCl、Na2SO4四种电解液中模板炭的电化学性能,发现模板炭在不同电解液中的比电容和循环伏安特性差别很大,在NaOH中的比容量、可逆性和循环伏安特性最好,在1.0mA时的比容量可达150.4F/g,在Na2SO4中的电容量最低,1.0mA时的比容量为58.7F/g。原因主要是随着电解质离子半径的增大,在模板炭孔隙中的扩散阻力增加。采用改进的Hummers方法制备了氧化石墨,在水中经超声分散得到片层直径0.4μm左右的单片层氧化石墨烯胶体溶液,经硼氢化钠还原得到比表面积为358 m2/g的石墨烯,在充放电电流为10 mA时,石墨烯电极的充电比容量可达138.6 F/g,充放电效率为98%。与微孔炭相比,开放平面的石墨烯具有较高的面积比电容。以5.0～50 mV/s扫描速率进行循环伏安测试,石墨烯电极表现出良好的功率性能。更多还原

【Abstract】 Supercapacitors have been arousing more attentions in newly developed fields like electronics, new power sources etc. Since their performance mainly depends on the anode materials, it has been extensively pursued to get high quality materials with low cost and easy ways.Carbon foams with three dimensional networks and microsize walls were prepared from a pitch and a phenolic resin respectively through foaming, carbonization. The carbon foams were activated with steam activation. A microporous template carbon was synthesized from furfuryl alcohol with NaY zeolite as the template. Graphene was converted from natural crystalline flake graphite by modified hummers’method. The manufactured carbons, which could be classified into microporous and opened planar structured carbons, were evaluated with cyclic voltammetry and constant current coulometry for electrode materials of supercapacitors. The effect of pore size and electrolyte ions on capacitance was discussed.A thermalplastic phenolic resin blinded with hexamine was heated to foam at about 210℃, and then heated to 700℃to transform into carbon foams, among which the sample derived with 12wt% hexamine heated at 10℃/min. The carbon foam was activated at 700-850℃for 60-180min with water steam metered by water flow of 1.0-2.0mL/min, into activated carbon foams with specific surface area of 474-1287m2/g and pore diameter of 0.64-5.0nm. While a pitch with soft-point of 285℃was blown to pitch foams by supercritical solvent and successively oxidized and carbonized to get carbon foams, on which the solvent addition, foaming temperature, and initial pressure were the key influencial factors. The sample foamed under the conditions of 30wt% toluene, initial pressure of 3.0MPa, and foaming temperature of 300℃. was activated at 850℃for 60-180min with water steam metered by water flow of 1.0mL/min, into activated carbon foams with specific surface area of 399-953m2/g and pore diameter of 0.59-5.0nm.The electrochemical performances of the two activated carbon foams was studied, the phenolic resin based and the pitch based with specific surface area of 961m2/g and 953m2/g respectively. When measured at the current of 1.0mA, the two samples owned the similar capacitances of 117F/g and 112.5F/g, while measured at 50mA, their capacitances differed a lot, with 60.5F/g for the former and 28.3F/g for the later. Compared with activated carbon fiber with specific surface area of 1297m2/g, the activated resin carbon foam with specific surface area of 1267 m2/g showed a comparable specific capacitance of 142.4 F/g against 169.8F/g at 1.0mA and decreased to 77.1F/g against 121F/g at 50mA, indicating that activated carbon foam would be a good electrode material with easy process even a little lower performance compared with activated carbon fiber.Template carbons were prepared from furfuryl alcohol by using NaY zeolite as the template through soaking, polymerizing, carbonizing at 700-800℃, template removing with HF, with pores sized at 1.0nm and 1.6nm and specific surface area of 578-826m2/g. The sample with specific surface area of 826m2/g were measured in four different electrolytes of NaOH, KOH, NaCl and Na2SO4, showing that the performance in NaOH was the best with capacitance of 150.4F/g at 1.0mA, while that in Na2SO4 was the worst, with capacitance of 58.7F/g. The reason could be interpreted as smaller ions diffused more easily in the micropores.Graphene was converted from a crystal flake graphite through oxidizing by modified Hummers’method, dispersing by supersonic and reducing by NaBH4, with specific surface area of 358m2/g. The specific capacitance could reach 138.6F/g at 10mA with a capacitance efficiency of 98%, much higher than the micropore carbons based its specific surface area, which could be mainly benefited from its opened planar structure. The cyclic voltammetry showed the graphene had good double layer capacity.更多还原