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基于棉花的多孔碳材料制备及其在超级电容器领域的应用
张岚
Subtype硕士
Thesis Advisor张亚刚
2018-05-24
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline材料工程
Keyword多孔碳材料 棉花 超级电容器 电化学性能
Abstract

随着经济社会的快速发展,化石能源的大量消耗和日益枯竭以及人们对环境污染的不断重视,对于新能源汽车的呼声越来越高,二次联用电池的发展也越来越迫切。不少研究者将研究的重点集中在了寻找充放电迅速且稳定,成本低,循环稳定性高的且环境友好型的新能源材料的研究上。超级电容器拥有比电容较高,循环稳定性好,价格低廉以及环境友好,功率密度高等一系列优点,而逐渐成为人们研究和开发的重点。由于生物质原材料来源非常丰富,种类众多,并且价格低廉,具有可再生性等优点,是较为有潜力的制备多孔碳材料的主要原料。本文以大宗可再生农产品棉花为原料,利用简单便捷环保的一步碳化活化法,制备氮和氧掺杂的多孔碳材料,并对其电化学性能进行了系统地表征。本论文所做的工作如下:1 以KOH为活化剂,棉花为原料,选取700 ℃,800 ℃及900 ℃三个不同温度下碳化活化,制备出具有高性能的多孔碳材料,将其用作超级电容器的电极材料,命名为COH-700,COH-800及COH-900。其中,COH-800具有1268.6 m2 g-1的高比表面积。在三电极体系下,碱性电解液中,当电流密度为0.5 A g-1时,比电容达到252 F g-1。在双电极体系下,当电流密度为0.5 A g-1时,比电容容量能达到229 F g-1,当电流密度达到10 A g-1时,材料的大电流下的比电容的保留率为86 %,倍率特性优异。同时,材料拥有良好的循环稳定性,经过10000次循环后,比电容依旧保持在初始值的88 %。优异的电化学性能,原料价格低廉且易得,加上制备方法简便的优点,这些使得COH-800在超级电容器领域有着较好的应用前景。2 以棉花为原料,以磷酸氢二氨(DAP)为活化剂以及氮源,经碳化与氧化后,制备出具有优异电化学性能的超级电容器电极材料。结果显示:磷酸氢二氨(DAP)不仅有助于材料碳化孔结构的生成,使碳材料比表面积增大,并且使得材料的产率得到显著提升(38 %),并且为碳材料内部成功引入了氮源。最终,经350 ℃ 氧化的材料(CDAP800-350)成功引入了大量的氧元素,提高了材料表面的润湿性。CDAP800-350的表面积可达1200 m2 g-1,同时电化学性能表现出色,在三电极体系中,在电流密度为0.5 A g-1,6M KOH电解液中比电容可达292 F g-1,并且在电流密度为10 A g-1时,比电容容量达到233 F g-1,表明其具有优异的倍率特性(保留率为初始的80 %)。此外,在5 A g-1的电流密度下循环5000次后,比电容容量仍可保持初始容量的92 %。在双电极体系中,6 M KOH为电解液,CDAP800-350比电容可达270 F g-1,并且在电流密度为10 A g-1时比电容容量为212 F g-1,表明其具有优异的倍率特性(保留率为初始的79 %)。此外,循环5000次后材料的电化学性能并未大幅衰减,可以维持在初始值的86 %左右。在功率密度最高达到250 W kg-1时,能量密度最高可达18 W kg-1。

Other Abstract

The development of new materials for energy storage system has attracted tremendous attention. With rapid consumption and limited availability of fossils fuels, designing functional materials for sustainable and alternative energy is feasible and promising approach. Researchers have focused on the design of new energy materials that are capable of quick charging and discharging, performance stable, low cost, high cycle stability and environmentally benign. Supercapacitors have be widely used in commercial and industrial equipments because of their high power density, short charge-discharge times and longer life span compared with traditional energy storage devices. Compared to the fossil-fuel based approach, the biomass-derived porous carbon materials feature distinct advantages, such as low-cost, desirable availability and sustainability. Herein, we reported a facial, green and highly efficient strategy for preparing nitrogen and oxygen doped porous carbon for supercapacitors electrode from bio-based based cotton resource.1. Absorbent cotton was used as starting materials and KOH were used as activated. Cotton were oxidized at different temperature 700 ℃, 800 ℃ and 900 ℃ designated as COH-700,COH-800 and COH-900, respectively. COH-800 showed the highest BET surface area (1268.6 m2 g-1) and superior electro-chemical property. In three-electrode system, the COH-800 electrodes had specific capacitances as high as 252 F g-1 in 6 mol KOH electrolyte at a current density of 0.5 A g-1. In the two-electrode system, CDAP800-350 electrode displayed a specific capacitance of 229 F g-1 at 0.5 A g-1 and 212 F g-1 at 10 A in KOH electrolyte, respectively, the retention is 86 %. In addition, the CDAP800-350 based symmetric supercapacitor achieved a high stability with 88% of capacitance retention after 10000 cycles at 5 A g-1.2. Absorbent cotton was used as starting materials and diammonium hydrogen phosphate (DAP) was used as both doping and activation reagent. DAP was not only more eco-friendly and economy, but also significantly improved the final yield of porous carbon product (by 38 %), which was improved about 3 folders than unimpregnated cotton. Furthermore, DAP was found to be an effective N doping reagent. Oxidation treatment helped introducing O elements, which facilitated better surface wettability. Finally, the sample oxidized at 350 ℃ (CDAP800-350) demonstrated superior electro-chemical performance. CDAP800-350 showed the highest BET surface area (1022 m2 g-1) and relatively high pore volume (0.53 cm3 g-1). In three-electrode system, the CDAP800-350 electrodes had high specific capacitances of 292 F g-1 in 6 mol KOH electrolyte at a current density of 0.5 A g-1. In the double-electrode system, CDAP800-350 electrode displayed a specific capacitance of 270 F g-1 at 0.5 A g-1 and 212 F g-1 at 10 A in KOH electrolyte, respectively. In addition, the CDAP800-350 based symmetric supercapacitor achieved a high stability of 87 % of capacitance retention after 5000 cycles at 5 A g-1, as well as a high volumetric energy density (18 Wh kg-1 at 250 W kg-1).

Pages66
Document Type学位论文
Identifierhttp://ir.xjipc.cas.cn/handle/365002/5434
Collection资源化学研究室
Recommended Citation
GB/T 7714
张岚. 基于棉花的多孔碳材料制备及其在超级电容器领域的应用[D]. 北京. 中国科学院大学,2018.
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