纤维基锂离子电容器的构建及电化学性能研究
发布时间：2019-03-22 08:56
【摘要】：本论文创新性地提出了一种自支撑全纤维基锂离子电容器的构建方法。利用静电纺丝工艺以及简单的热处理方法分别制备了柔性酚醛基介孔炭纳米纤维和聚丙烯腈/木质素基复合炭纳米纤维,通过优化配比选择最佳的纳米炭纤维薄膜电极。之后将预嵌锂后的聚丙烯腈/木质素基复合炭纳米纤维作为负极,跟正极酚醛基介孔炭纳米纤维组装成全纤维基锂离子电容器。分别对正、负极材料的结构、形貌以及组装成器件的电化学性能作了较为系统的研究。首先,以热固性酚醛树脂为炭前躯体,嵌段共聚物F127为模板剂,聚乙烯醇缩丁醛为助纺剂,通过静电纺丝和炭化过程制备了柔性酚醛基介孔炭纳米纤维。通过优化配比,得到具有丰富介孔结构的炭纳米纤维。并且将其直接作为自支撑活性材料组装成水系电容器,在0.05 A g-1的电流密度下,纤维电极获得139.6 F g-1的放电比电容量;当电流密度达到5 A g-1时,比电容仍然能够达到97.34 F g-1,证明酚醛基介孔炭纤维杰出的倍率性能。其次,以聚丙烯腈和木质素做为炭源,通过静电纺丝制备聚丙烯腈/木质素基复合炭纳米纤维。优化聚丙烯腈和木质素的配比,将其分别组装成锂离子半电池,获得具有优秀倍率性能以及长循环稳定性的复合炭纳米纤维PL-5/5电极。并将其进行改性,成功地构建了相邻纤维互相焊接且具有介孔通道的复合炭纳米纤维膜,纤维电极展现出了 384.4mAhg-1的可逆容量,以及大电流充放电(5Ag-1)条件下,仍能够保持较好的放电容量127.7 mAh g-1,并且其放电时间仅为91s。最后,以酚醛基介孔炭纳米纤维作为正极活性材料,预嵌锂后的聚丙烯腈/木质素基复合炭纳米纤维作为负极活性材料,在没有导电剂以及集流体的情况下,成功的构建了自支撑全纤维基锂离子电容器。通过电化学性能研究,发现当能量密度为72.62 Whkg-1时,功率密度为97.62 Wkg-1;并且当能量密度为33.05 Wh kg-1,功率密度可高达11.89 kWkg-1,证明其优秀的能量和功率特性;并且在0.5 Ag-1的电流密度下经过2100个循环之后,仍然能保持初始容量的91.94%,进一步说明其优秀的循环稳定性。
[Abstract]:In this paper, a novel method of constructing self-supporting all-fiber based lithium-ion capacitors is proposed. Flexible phenolic-based mesoporous carbon nanofibers and polyacrylonitrile / lignin-based composite carbon nanofibers were prepared by electrospinning and simple heat treatment. The best carbon fiber thin-film electrodes were selected by optimizing the ratio of carbon nanofibers to polyacrylonitrile / lignin-based carbon nanofibers. Then the polyacrylonitrile / lignin-based composite carbon nanofibers were used as negative electrodes and the positive phenolic-based mesoporous carbon nanofibers were assembled to form all-fiber-based lithium-ion capacitors. The structure, morphology and electrochemical performance of positive and negative materials were studied systematically. Firstly flexible phenolic-based mesoporous carbon nanofibers were prepared by electrospinning and carbonization using thermosetting phenolic resin as carbon precursor block copolymer F127 as template and polyvinyl butyral as spinning aid. Carbon nanofibers with rich mesoporous structure were obtained by optimizing the ratio. At the current density of 0.05A 路g ~ (- 1), the discharge specific capacitance of 139.6 F / g 路L ~ (- 1) was obtained at the current density of 0.05A 路g ~ (- 1), which was assembled directly as a self-supporting active material. When the current density reaches 5 A g ~ (- 1), the specific capacitance can still reach 97.34 F / g ~ (- 1), which proves that the phenolic-based mesoporous carbon fiber has excellent ratio performance. Secondly, polyacrylonitrile / lignin composite carbon nanofibers were prepared by electrospinning using polyacrylonitrile and lignin as carbon source. The ratio of polyacrylonitrile (pan) and lignin (lignin) was optimized and assembled into lithium ion semi-battery respectively. The composite carbon nanofiber PL-5/5 electrode with excellent performance and long cycle stability was obtained. The composite carbon nanofiber membrane with mesoporous channels and welded adjacent fibers was successfully constructed. The reversible capacity of 384.4mAhg-1 and the high current charge / discharge (5Ag-1) condition of the fiber electrode were demonstrated. It is still able to maintain a good discharge capacity of 127.7 mAh / g / kg, and the discharge time is only 91 s. Finally, phenolic-based porous carbon nanofibers were used as positive active materials, polyacrylonitrile / lignin-based composite carbon nanofibers pre-intercalated with lithium were used as negative active materials. The self-supporting all-fiber-based lithium-ion capacitor was successfully constructed. It is found that when the energy density is 72.62 Whkg-, the power density is 97.62 Wkg-1;. When the energy density is 33.05 Wh kg-1, the power density can be up to 11.89 kWkg-1, to prove its excellent energy and power characteristics. After 2100 cycles at the current density of 0.5 Ag-1, the initial capacity can still be kept 91.94%, which further explains its excellent cycle stability.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53
本文编号：2445450
[Abstract]:In this paper, a novel method of constructing self-supporting all-fiber based lithium-ion capacitors is proposed. Flexible phenolic-based mesoporous carbon nanofibers and polyacrylonitrile / lignin-based composite carbon nanofibers were prepared by electrospinning and simple heat treatment. The best carbon fiber thin-film electrodes were selected by optimizing the ratio of carbon nanofibers to polyacrylonitrile / lignin-based carbon nanofibers. Then the polyacrylonitrile / lignin-based composite carbon nanofibers were used as negative electrodes and the positive phenolic-based mesoporous carbon nanofibers were assembled to form all-fiber-based lithium-ion capacitors. The structure, morphology and electrochemical performance of positive and negative materials were studied systematically. Firstly flexible phenolic-based mesoporous carbon nanofibers were prepared by electrospinning and carbonization using thermosetting phenolic resin as carbon precursor block copolymer F127 as template and polyvinyl butyral as spinning aid. Carbon nanofibers with rich mesoporous structure were obtained by optimizing the ratio. At the current density of 0.05A 路g ~ (- 1), the discharge specific capacitance of 139.6 F / g 路L ~ (- 1) was obtained at the current density of 0.05A 路g ~ (- 1), which was assembled directly as a self-supporting active material. When the current density reaches 5 A g ~ (- 1), the specific capacitance can still reach 97.34 F / g ~ (- 1), which proves that the phenolic-based mesoporous carbon fiber has excellent ratio performance. Secondly, polyacrylonitrile / lignin composite carbon nanofibers were prepared by electrospinning using polyacrylonitrile and lignin as carbon source. The ratio of polyacrylonitrile (pan) and lignin (lignin) was optimized and assembled into lithium ion semi-battery respectively. The composite carbon nanofiber PL-5/5 electrode with excellent performance and long cycle stability was obtained. The composite carbon nanofiber membrane with mesoporous channels and welded adjacent fibers was successfully constructed. The reversible capacity of 384.4mAhg-1 and the high current charge / discharge (5Ag-1) condition of the fiber electrode were demonstrated. It is still able to maintain a good discharge capacity of 127.7 mAh / g / kg, and the discharge time is only 91 s. Finally, phenolic-based porous carbon nanofibers were used as positive active materials, polyacrylonitrile / lignin-based composite carbon nanofibers pre-intercalated with lithium were used as negative active materials. The self-supporting all-fiber-based lithium-ion capacitor was successfully constructed. It is found that when the energy density is 72.62 Whkg-, the power density is 97.62 Wkg-1;. When the energy density is 33.05 Wh kg-1, the power density can be up to 11.89 kWkg-1, to prove its excellent energy and power characteristics. After 2100 cycles at the current density of 0.5 Ag-1, the initial capacity can still be kept 91.94%, which further explains its excellent cycle stability.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53
【参考文献】
相关期刊论文 前2条
1 蔡少伟;;锂离子电池正极三元材料的研究进展及应用[J];电源技术;2013年06期
2 杨绍斌,胡浩权;锂离子电池[J];辽宁工程技术大学学报(自然科学版);2000年06期
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