盐溶液活化木质纤维素碳材料及其电容性能研究

发布时间：2018-04-08 18:20

  本文选题：生物质碳材料　切入点：双电层电容器　出处：《中南林业科技大学》2017年硕士论文

【摘要】：碳材料由于具有良好的导电性、热稳定性、高比表面积、较高的机械强度等特点,在吸附材料、催化材料、电极材料、生物载体等领域都具有良好的应用前景,近年来受到了国际上众多学者的广泛关注。现阶段,碳材料的主要原料来源还主要依赖于石油、煤炭等矿产资源,而随着这些不可再生资源的日益消耗,这些资源的可开采年限正在急剧减少,因此,寻找一种可替代的可再生资源用于制备高活性的碳材料迫在眉睫。生物质资源如作物秸秆、林业剩余物、禽畜粪便等,不仅具有廉价、来源广泛、环境友好等优点,其碳材料一般还含有丰富的羟基、羧基等含氧官能团,这些官能团在催化材料、电极材料、生物载体等领域都具有十分重要的作用,近年来受到了学术界的广泛关注。近十年来,科学家针对生物质碳材料来源、生物质碳材料制备方法和生物质碳材料活化机理三个方面都做了系统的研究。在研究过程中发现,生物质原材料经过简单的高温碳化后其比表面积仍然无法满足吸附材料、电极材料的要求。因此,在生物质碳材料制备过程中常需加入活化剂对生物质碳材料进行活化处理,而常用的活化剂如强碱、强酸、强碱盐等长期使用会腐蚀工业设备增加企业成本,这一直是生物质碳材料工业化生产中的存在的问题。针对这一问题,本论文选用纤维素为碳源,探究NaH2PO4、ZnCl2以及其混合盐溶液对生物质碳材料微观形貌、孔隙结构、电容性能的影响及活化机理。实验结果表明:(1)NaH2PO4溶液可通过提高碳材料的石墨化程度,提升碳材料在电解液中的润湿性和导电性,从而改善纤维素碳材料的电容性能。纤维素碳材料的石墨化程度和NaH2PO4溶液浓度有着密切关系,当NaH2PO4溶液浓度为200mg/mL时,纤维素碳材料比电容提升效果最明显,在1 Ag-1的电流密度下,其比电容可达到123 Fg-1。(2)ZnCl2溶液可通过提高碳材料的比表面积,并引进大量含氧官能团,加速电解液中的电荷在多孔碳材料中的传递,从而改善纤维素碳材料的电容性能。纤维素碳材料的多孔结构和ZnCl2溶液浓度有着密切关系,当ZnCl2溶液浓度为100 mg/mL时,纤维素碳材料比电容提升效果最明显,在1Ag-1的电流密度下,其比电容可达到141.4Fg-1;(3)NaH2PO4-ZnCl2溶液可通过调整纤维素碳材料的微孔与介孔比例,制备磷元素掺杂的等级多孔结构的碳材料进一步优化纤维素碳材料的电容性能。纤维素碳材料的等级多孔结构和NaH2PO4-ZnCl2溶液浓度比例有着密切关系,当NaH2PO4-ZnCl2溶液浓度都为100mgmL-1时,纤维素碳材料比电容提升效果最明显,在1Ag-1的电流密度下,其比电容可达到195.1 F g-1;(4)以最佳优化条件制备的PZCC100碳材料为电极组装对称性双电层电容器,在6MKOH电解液中所能达到最大的能量密度可达到4.7 Whkg-1,明显高于许多已报道的碳材料双电层电容器,且具有十分优异的电化学稳定性,循环10000次后电容基本无明显衰减,仍能保持在原比电容的96.7%左右。
[Abstract]:Carbon material due to its electrical conductivity, good thermal stability, high surface area, high mechanical strength, the adsorption materials, catalytic materials, electrode materials, and has good application prospects in areas such as biological carrier, in recent years by international scholars wide attention. At present, the main raw material of carbon source the material is mainly dependent on oil, coal and other mineral resources, and with the increasing consumption of these non renewable resources, these resources can be exploited is drastically reduced, therefore, looking for an alternative and renewable resource for imminent preparation of high active carbon materials. Biomass resources such as crop straw, forestry residues, livestock feces, not only has the advantages of low cost, wide source, environmentally friendly, the carbon material generally is also rich in hydroxyl, carboxyl functional groups, these functional groups in catalytic materials, electrode Materials, plays an important role in areas such as biological carrier, in recent years has been widespread concern in academic circles. In the past ten years, scientists at the biomass carbon source material, three aspects of biomass carbon materials and preparation methods of biomass carbon materials activation mechanism were systematically studied. During the course of the study, biomass the raw material after high temperature carbonization simple after the surface area is still unable to meet the requirements of adsorption materials, electrode materials. Therefore, the biomass carbon materials in the preparation process often need to add activator of biomass based carbon materials were activated, and the activation agent such as alkali, acid alkali salt commonly used, long-term use will increase the enterprise the cost of corrosion of industrial equipment, which has been the problem of biomass carbon materials in industrial production. In order to solve this problem, this paper adopts cellulose as the carbon source, research NaH2PO4, ZnCl2 and The mixed salt solution on biomass carbon material microstructure, pore structure, and the influence mechanism of activation capacitance performance. Experimental results show that: (1) NaH2PO4 solution can improve the degree of graphitization of carbon materials, carbon materials enhance the wettability and conductivity in the electrolyte, thus improving the capacitance properties of cellulose carbon materials graphite. The degree of concentration of NaH2PO4 and cellulose carbon materials have a close relationship, when the NaH2PO4 concentration is 200mg/mL, the cellulose specific capacitance of carbon material enhance the most obvious effect on the current density of 1 Ag-1, the specific capacitance can reach 123 Fg-1. (2) ZnCl2 solution by increasing the specific surface area of carbon materials, and the introduction of a large number of oxygen-containing functional groups, accelerating charge in the electrolyte in the porous carbon material transfer, thereby improving the capacitance performance of carbon materials cellulose. Cellulose carbon material of the porous structure and the concentration of ZnCl2 solution is A close relationship, when the ZnCl2 concentration is 100 mg/mL, the specific capacitance of cellulose carbon materials to enhance the effect, the current density of 1Ag-1, the specific capacitance can reach 141.4Fg-1; (3) NaH2PO4-ZnCl2 solution by adjusting the proportion of cellulose microporous and mesoporous carbon material, the capacitance performance level of the porous structures of carbon materials preparation of phosphorus doped carbon materials to further optimize the cellulose. Cellulose carbon material grade porous structure and NaH2PO4-ZnCl2 concentration ratio has a close relationship, when the NaH2PO4-ZnCl2 concentration is 100mgmL-1, the cellulose specific capacitance of carbon material, enhance the most obvious effect on the current density of 1Ag-1, the specific capacitance can reach 195.1 F g-1; (4) PZCC100 carbon materials to the optimization conditions for preparation of electrode assembly symmetry of electric double layer capacitor, which can achieve the maximum energy density can reach 4.7 W in 6MKOH solution. Hkg-1 is much higher than many of the reported carbon materials, and has excellent electrochemical stability. After 10000 cycles, the capacitance is basically not attenuated, and it can still maintain about 96.7% of the original capacitance.

【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TM53
，

本文编号：1722783