Preparation And Energy Storage Application Of Heteroatom-Doped Graphdiyne Materials

In recent years,the rapid development of smart wireless devices has promoted further exploration of energy storage batteries.Therefore,research on high-performance energy storage electrode materials has become the focus of materials and energy field.Carbon-based materials have received widespread attention as cost-effective energy storage materials.The well-studied carbon materials include graphite,carbon nanotubes,graphene,and graphdiyne(GDY).Among them,GDY is a new carbon material successfully prepared in 2010.The 18-carbon triangular pores in GDY provides transport channels for metal ions,especially lithium ions.In addition,a large number of alkyne bonds in the structure endow GDY good electrocatalytic properties.In this thesis,we doped GDY with heteroatoms to adjust the structure and electronic distribution,resulting improved energy storage and electrocatalytic performance.The main research is divided into the following three parts.(1)An evenly co-doped GDY with H and F(H1F1-GDY)was prepared through a coupling reaction on copper foil,and tested as anode for lithium ion batteries(LIBs).The replacement of H can increase the specific capacity of material and obtain cost reduction.The introduce of F can effectively improve the wettability with organic electrolyte,and the C-F bonds are very conducive to the formation of stable solid electrolyte interface(SEI)film,which benefit the long-term stability of the electrode material.The as prepared material has superior conductivity and a fibrous network porous structure that further enhances the interface compatibility.Under the synergistic effect of H and F,H1F1-GDY reaches a specific capacity of 2050 mAh g-1 at current density of 50 mA g-1.At 5 A g-1,it can still retain a specific capacity of 77%after 8000 cycles of stable operation.Only 4%of the capacity is lost after a stable operation of 3000 cycles at 2 A g-1.(2)The spirobifluorene-based GDY(SBF-GDY)was prepared by combining the spirobifluorene structure with the alkyne bond,and then applied it to lithium ion batteries.Due to the twisted structure of spirobifluorene,the as-prepared SBF-GDY presents a shape of solid sphere.The spherical structure greatly reduces the defects and edges in structure,thereby reducing the generation of irreversible lithium storage sites.The abundant benzene rings and alkyne bonds provide rich lithium storage sites.In addition,the large pores with a diameter of 1.59 nm mainly distributed in the structure provide convenient and efficient transmission channels for lithium ions.Finally,the lithium storage specific capacity of 1055 mAh g-1 was obtained,moreover,the original capacity can be basically maintained after 8500 cycles of stable operation at 5 A g-1.(3)Lithium-ion capacitor(LIC)is promising energy storage device that have been studied in recent years which combining the advantages of LIB and electric double-layer capacitors(EDIC).The energy storage performance of LIC anode materials is an important aspect that decides the performance of LIC.We used H substituted GDY(HGDY)as the anode and activated carbon(AC)as the cathode to assemble the LIC,and compared the performance of the assembled LIC by adjusting the ratio of activated carbon to HGDY.The results show that the energy density decreases with the proportion of AC increases.When HGDY:AC=1:4,the energy density is 135 Wh kg-1 and the LIC assembled at HGDY:AC=1:2 can reach an energy density of 250 Wh kg-1 in the voltage range of 4.0-2.0 V.