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Supercapacitor Electrode Materials from Highly Porous Carbon Nanofibers with Tailored Pore Distributions

机译：具有高度定制的孔分布的高多孔碳纳米纤维制成的超级电容器电极材料

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摘要

Environmental and human health risks associated with the traditional methods of energy production (e.g., oil and gas) and intermittency and uncertainty of renewable sources (e.g., solar and wind) have led to exploring effective and alternative energy sources to meet the growing energy demands. Electricity based on energy storage devices are the most promising solutions for realization of these objectives. Among the energy storage devices, electrochemical double layer capacitors (EDLCs) or supercapacitors have become an attractive research interest due to their outstanding performance, especially high power densities, long cycle life and rapid charge and discharge times, which enables them to utilize in many applications including consumer electronics and transportation, where high power is needed. However, low energy density of supercapacitors is a major obstacle to compete with the commercially existing high energy density energy storage device such as batteries. The fabrication of advanced electrodes materials with very high surface area from novel precursors and utilization of electrolytes with higher operating voltages are essential to enhance energy density of supercapacitors. In this work, carbon nanofibers (CNFs) from different polymer precursors with new fabrication techniques are explored to develop highly porous carbon with tailored pore distributions to match with employed ionic liquid electrolytes (which possess high working voltages), to realize high energy storage capability. Novel electrode materials derived from electrospun immiscible polymer blends and synthesized copolymers and terpolymers were described. Pore distributions of CNFs were tailored by varying the composition of polymers in immiscible blends or varying the monomer ratios of copolymer or terpolymers.;Chapter 1 gives the detailed introduction of supercapacitors including history and storage principle of EDLCs, fabrication of carbon nanofiber based electrodes and electrolytes employed for EDLCs. It also explains the necessity and the advantages of tailored high surface area nanofibers as an electrode materials for supercapacitors.;Chapter 2 describes the preparation of high surface area carbon nanofibers using polymer blends containing PAN and PMMA and introduces an effective and simple strategy to improve the surface area of CNFs by using a sacrificial polymer, PMMA.;Chapter 3 describes blending of high fractional free volume polymer, 6FDA-DAM: DABA (3:2) into PBI to increase surface area and by using the higher etch rate of 6FDA-DAM: DABA in the blend to optimize pore distribution of CNFs.;Chapter 4 introduces a novel approach to increase surface area of CNFs without any physical or chemical activation by using an in situ porogen containing copolymer P(AN-co-IA). The concept developed here avoids unnecessary and complex extra activation steps when fabricating carbon nanofibers which leads to lower char yield and uncontrollable pore sizes.;Chapter 5 describes enhancement of surface area by using terpolymer P(AN-VIM-IA) to develop a new precursor. This approach is further advantageous since terpolymer can combine superior electrochemical properties of homopolymer, PAN and P(AN- co-IA) and P(AN-co-VIM).;Chapter 6 describes the use of commercially available small molecule compatibilizer 2-MI to tailor pore architecture of carbon fiber derived from the immiscible blend of PBI/6FDD to match with the ion sizes of ionic liquid electrolytes thereby increasing the surface area of the CNFs that is accessible to electrolytes.
机译：与传统能源生产方法（例如石油和天然气）以及可再生资源（例如太阳能和风能）的间歇性和不确定性相关的环境和人类健康风险已导致人们探索有效的替代能源以满足不断增长的能源需求。基于能量存储设备的电力是实现这些目标的最有希望的解决方案。在储能设备中，电化学双层电容器（EDLC）或超级电容器由于其出色的性能（尤其是高功率密度，长循环寿命以及快速的充电和放电时间）而引起了人们的研究兴趣，使其能够在许多应用中使用包括需要高功率的消费类电子产品和运输工具。然而，超级电容器的低能量密度是与诸如电池之类的商业上现有的高能量密度储能装置竞争的主要障碍。由新型前驱体制造具有非常高表面积的先进电极材料以及利用具有更高工作电压的电解质对于增强超级电容器的能量密度至关重要。在这项工作中，采用新的制造技术研究了来自不同聚合物前体的碳纳米纤维（CNF），以开发具有定制孔分布的高多孔碳，以与使用的离子液体电解质（具有高工作电压）相匹配，以实现高能量存储能力。描述了由电纺不混溶的聚合物共混物以及合成的共聚物和三元共聚物衍生的新型电极材料。通过改变不溶混共混物中聚合物的组成或改变共聚物或三元共聚物的单体比例来定制CNF的孔分布。第1章详细介绍了超级电容器，包括EDLC的历史和存储原理，碳纳米纤维基电极和电解质的制造用于EDLC。还解释了定制高表面积纳米纤维作为超级电容器电极材料的必要性和优势;第二章介绍了使用包含PAN和PMMA的聚合物共混物制备高表面积碳纳米纤维的方法，并介绍了一种有效而简单的策略来改善碳纳米管的性能。第3章介绍了将高分数自由体积聚合物6FDA-DAM：DABA（3：2）掺混到PBI中以增加表面积并使用更高的6FDA- DAM：共混物中的DABA，以优化CNF的孔分布。;第4章介绍了一种新方法，该方法通过使用原位含成孔剂的共聚物P（AN-co-IA）来增加CNF的表面积而无任何物理或化学活化。此处开发的概念避免了在制造碳纳米纤维时不必要和复杂的额外活化步骤，从而导致较低的炭收率和不可控制的孔径。;第5章介绍了通过使用三元共聚物P（AN-VIM-IA）开发新的前体来增加表面积的方法。 。由于三元共聚物可以结合均聚物，PAN和P（AN-co-IA）和P（AN-co-VIM）的优异电化学性能，因此该方法更具优势。;第6章介绍了使用市售的小分子增容剂2-MI调整源自PBI / 6FDD不混溶共混物的碳纤维的孔结构，使其与离子液体电解质的离子尺寸匹配，从而增加电解质可接近的CNF的表面积。

著录项

  • 作者

    Chathurika Abeykoon, Nimali.;

  • 作者单位

    The University of Texas at Dallas.;

  • 授予单位 The University of Texas at Dallas.;
  • 学科 Physical chemistry.;Polymer chemistry.;Materials science.
  • 学位 Ph.D.
  • 年度 2017
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 康复医学;
  • 关键词

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