QIBEBT-IR  > 仿生与固态能源系统研究组
Thesis Advisor黄长水 ; 崔光磊
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline材料学
Keyword石墨炔 氮掺杂 储锂/钠性能 多孔结构 电化学性能
Abstract碳材料作为下一代储能器件的电极材料已经得到了广泛研究。近年来,一种由sp和sp2杂化形成的新型碳的同素异形体石墨炔,由于其特殊的结构及优异的电子、光学和机械性能,引起了物理、化学以及材料学家的高度关注。在本论文中,我们主要致力于研究石墨炔薄膜与粉末的电化学储能性能,阐明其储锂/储钠机制,并且通过氮掺杂来改善其电化学性能。研究工作主要分为以下几个方面: (1) 采用六炔基苯在铜片的催化作用下发生交叉偶联反应,在铜片表面制备了三种不同厚度的大面积石墨炔薄膜。在不添加任何导电剂和粘结剂的条件下直接应用于锂电池中,并对其储锂性能及储锂机制进行了研究。实验结果表明制备的石墨炔薄膜具有优良电化学性能,包括较高的比容量,优异的倍率性能以及长的循环寿命。此外,石墨炔储锂机制是一个嵌入和吸附混合的过程。石墨炔具有均一的类似三角形的孔道结构,这种独特的结构赋予石墨炔更多的储锂位点,并且更加有利于离子和电子的传输,从而使得石墨炔具有优良的电化学储锂性能。 (2) 将生长在铜片上的石墨炔薄膜在氨气中进行高温处理,得到了大面积氮掺杂石墨炔薄膜;并将其应用于锂电池中对其储锂性能进行了研究。实验结果表明,相比于石墨炔,氮掺杂石墨炔展现了更加优异的倍率性能和循环性能,以及更高的容量。由于氮原子的引入,不但改善了石墨炔的电子结构,而且产生了更多的缺陷和活性位点,从而获得了更加优异的电化学性能。此外,氮原子的引入可能降低了电极表面副反应的发生,有利于形成稳定的界面,从而改善了循环过程中电极的稳定性。研究结果表明氮掺杂是一种有效改善石墨炔电化学性能的方法,氮掺杂石墨炔是一种非常有潜力的新型电极材料。 (3) 通过将铜片换成铜粉制备了多孔结构的石墨炔粉末,并对其形貌和结构进行了一系列表征,随后对其储锂、储钠性能进行了研究。以多孔结构的石墨炔粉末为电极材料所组装的电池展现了优良的电化学性能。石墨炔大的比表面积和多孔结构不但增加了活性位点,而且更加有利于离子和电子在电极表面的快速传输,从而获得较高的容量和优异的倍率性能。此外石墨炔基的钠电池展现了1000圈以上的循环寿命,表明多孔石墨炔具有优良的循环稳定性。
Other AbstractCarbon-based materials have been extensively investigated for their applications as electrode materials of the next-generation energy storage devices. In recent years, graphdiyne (GDY), a novel carbon allotrope comprising sp- and sp2-hybridized carbon atoms, has attracted considerable attention from physical, chemical and material scientists due to its unique structure and its excellent electronic, optical as well as mechanical properties. In this thesis, we mainly focused our attention on investigating the electrochemical energy performance of GDY films and powders, explaining their mechanisms for lithium (Li) and sodium (Na) storage, and improving their electrochemical performance by N-doped. The concrete research contents are summarized as follows: (1) Three different large-area GDY films of controlled thickness were synthesized via an in situ cross-coupling reaction on copper foil from hexaethynylbenzene. GDY films were applied as electrode materials for Li batteries without the addition of any conductive additives or polymer binders to estimate the Li storage performance and mechanism. The research results indicate that GDY films exhibited excellent electrochemical performance, including high specific capacity, outstanding rate performance, and long cycle life. In addition, the Li storage in multilayer GDY occurs through the surface adsorption/desorption and interlayer insertion/extraction mechanism. The unique structure of GDY, with its numerous large triangle-like pores, endows it with more Li storage sites and facilitates the rapid transport of electrons and ions, making GDY with extraordinary electrochemical performance for Li storage. (2) N-GDY films with large-area were synthesized through a heat treatment process at NH3, and were applied as electrode materials for Li batteries to evaluate the Li storage properities. Compared with GDY, the assembled batteries based on N-GDY electrodes exhibited more excellent electrochemical performance, including outstanding rate performance, superior cycling stability and high reversible capacity. The introduction of N atoms not only improves the electronic structure, but also creates numerous heteroatomic defects and active sites, thus achieving enhanced electrochemical performance. In addition, N-doping may be benefical to minimize the surface side reactions of electrodes with the electrolyte and form stable interfaces, thus improving the electrochemical stability of N-GDY electrodes during cycling. These results indicate N-doping is an efficient method for improving the electrochemical performance of GDY, and N-GDY is a novel electrode material with enormous potential. (3) GDY powders were successfully synthesized by changing copper films into copper powders and a series of testing methods were carried out to characterize the morphology and structure of GDY powders, and then investigate the electrochemical performance for Li and Na storage. The assembled GDY-based cells exhibited excellent electrochemical performance. The unique structure of GDY with numerous micropores and mesopores endows GDY more active sites and facilitates the rapid transport of electrons and ions, thus achieving high specific capacity and excellent rate capability. In addition, the assembled GDY-based Na batteries deliver a long cycle life of more than 1000 cycles, indicating the excellent chemical stability of microporous and mesoporous GDY powders.
Date Available2018-09
Subtype硕士 ; 学位论文
Document Type学位论文
Recommended Citation
GB/T 7714
张圣亮. 石墨炔电化学储能性能研究[D]. 北京. 中国科学院大学,2015.
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