|Other Abstract||Carbon-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.|