| Graphdiyne represents a series of two-dimensional layered planar carbon materials composed of sp and sp~2 hybridized carbon atoms.As an emerging and promising member of the nanocarbon material family,it possess a number of configurational advantages,such ashighly conjugated morphology,rich carbon chemical bonds,uniformly distributed pore channels and controllable electronic structures.Therefore,it has many potential applications in fields,such as electronic information,energy transformation and storage,environment and separation,biological applications,catalysis,etc.The properties of graphdiyne is inherently related to its structure,and different nanostructured graphdiynes have different potential applications.Therefore,synthesis of graphdiyne with controlled structures is of great important.In this dissertation,graphdiynes with different morphological features were prepared by the polymerization reaction using either copper foam or silica nanospheres as template.the prepared graphdiyne was subsequently applied as the lithium selenium battery separator,which can avoid the the shuttle effect existed in other battery separatorsverifying the potential of graphdiyne in energy storage.The major content of the paper is as follows:1.By using a hexaethynylbenzene as a precursor,the alkyne-alkyne coupling reaction was carried out by the solution phase method in an organic solvent,pyridine.In this reaction,the pre-processed copper sheet was the base template of the reaction,and it was also the donor of copper ions.Pyridine was used as a solvent for the reaction,and at the same time,as an organic base to catalyze the production of copper ions.In addition,the pyridine could also complex with copper ions to catalyze this reaction.In this experiment,HEB-TMS was applied as a precursor to obtain the monomer HEB required for the reaction after the deprotection reaction,and then the graphdiyne powder with good growth was obtained by the reaction on a copper plate in the pyridine solvent.2?Hexaethynylbenzene was used as the monomer,and the Glaser-Hay terminal alkyne coupling reaction was performed in the organic phase solution.In this reaction,acetone was used as the solvent of the reaction,the pretreated copper foam sheet was the base plane template for the reaction and the donor for the copper ion catalyst,acetone and a small amount of pyridine were acted as the organic base.The morphology control of graphdiyne grown on copper foam can be regulated by the amount of organic base ligand concentration effectively,so as to overcome disadvantages of traditional graphdiyne solution phase synthesis method which utilized the pyridine as both an organic base ligand and a reaction solvent and it failed to accurately control the active site.The addition of TMEDA optimized the conditions for the formation of nanowall structures on copper foam,which could further promote the better controlled growth of the graphdiyne micro-morphology.3?Silica nanospheres were used as the growth substrate,a layer of copper was coated on the surface by a substitution reaction,and then the porous graphdiyne structure was grown on the nanospheres covered with the copper element.Under the growth and synthesis conditions of the graphdiyne nanowall structure,graphdiyne grew on the surfaces where the silica nanospheres contacted each other,so that a large number of silica nanospheres were agglomerated with each other to form a very dense graphdiyne cluster structure of silica nanospheres.After the template of silica nanospheres was removed by hydrofluoric acid to obtain a three-dimensiona porous graphdiyne structure.And with the extension of reaction time,the density and height of the obtained three-dimensional graphdiyne porous structure also increased.From the results of SEM and Raman characterization,it can be seen that the quality of graphdiyne generated under such conditions is good,which is in line with theoretical predictions.4?In this experiment,the prepared graphdiyne powder and polyvinylidene fluoride(PVDF)were mixed uniformLy in a determinate proportion,coated on a battery separator to make a battery separator modified by graphdiyne and applied to a lithium selenium battery.This system was carried out the rate charge and discharge test and voltammetric cycle test.The charge-discharge curve results showed that in the voltage range of 1.8 V-2.6 V,the lithium-selenium battery with a diaphragm modificated by the graphdiyne coating was very stable after a 100-cycle redox reaction.This indicates that the battery has good reversible redox activity and stability;this kind of lithium-selenium battery has excellent rate performance,and still has a higher specific capacity at a larger rate.The first turn of the lithium-selenium battery with a graphdiyne-coated modificated diaphragm discharged at a current density of 0.2 C(1 C=675 m A/g)not only reached the specific capacity of 579.4 mAh/g,but also achieved the Coulomb efficiency of 105.61%.Compared with the battery with a ordinary diaphragm,the first circle discharged at a current density of 0.2 C(1 C=675 mA/g)with the specific capacity of only 523.2 mAh/g,and the Coulomb efficiency was merely 122.12%.The lithium-selenium battery with a diaphragm modificated by the graphdiyne coating still had a specific capacity of 386 mAh/g after 100 turns,while the specific capacity of a common one was only 142.2 mAh/g.Therefore,the graphdiyne with large surface area and porous channel structure provide a new development direction for the research on energy storage of new lithium selenium batteries. |
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