Preparation Of Phosphononitrile-based Heteroatoms Doped Porous Carbon Materials And Their Performance Of Supercapacitors

Carbon materials are considered as electrode materials with great industrialization prospects due to their rich reserves,low cost,high stability and high conductivity.There are usually two methods to improve the charge storage capacity of carbon-based materials:Constracting hierarchical porous carbon with high specific surface area,rich porous structure and developing the heteroatom co-doped carbon.Hexachlorocyclotriphosphazene（HCCP）is a six-membered ring system with alternating phosphorus and nitrogen repeating atoms.It is prone to nucleophilic reactions and can be easily functionalized by selective substitution to generate various derivatives.Therefore,in this paper,HCCP is used as the raw material,and a series of heteroatom-doped porous carbon materials are prepared by different chemical reactions to be used as supercapacitor electrode materials,and the electrochemical performance of each material is studied.1.Using HCCP as raw material,hexaphenoxycyclotriphosphazene（HPCTP）was synthesized through nucleophilic substitution reaction.And three kinds of porous organic polymers（POPs）were synthesized by Friedel-Crafts reaction of HPCTP and different crosslinking monomers:HP-P-1,HP-P-2 and HP-P-3.The influence of different crosslinking monomers and different carbonization temperatures on the electrochemical performance of each material were studied.Then we focused on the electrochemical performance of HP-P-1 materials activated with different amounts of KOH at 800℃.The results show that the HP-P-1 material activated with 2 times the mass of KOH has the best performance.Its specific surface area is as high as 1095m²g^-1,and it is rich in pore structure;its nitrogen content is 1.07%,and its phosphorus content is 1.52%.In the three-electrode system,when the current density is 0.5 A/g,it has a specific capacity of 282 F/g,and when the current density is increased to 20A/g,it still has a specific capacity of 204 F/g.After being assembled into a symmetrical button supercapacitor,the energy density at a power density of 252 W kg^-1 is 7.36 Wh kg^-1,and 96.1%of the capacity remained after 10,000 cycles.2.,Hexaphenylaminocyclotriphosphazene（HACTP）was synthesized by HCCP and aniline.We hope to increase the nitrogen content in the material by converting the PO bond of the polymer into P-N bond in the previous work Then,using Friedel-Crafts reaction to react hexaphenylamino cyclotriphosphazene with different cross-linking monomers to prepare three porous organic polymers（POPs）:HA-P-1,HA-P-2 and HA-P-3,SEM results show that different crosslinking monomers will affect the morphology of the product,and the carbonization of various series of materials at different temperatures,the electrochemical performance test shows that the HA-P-2 material has better performance than the other two materials Afterwards,we focused on the effect of the amount of activator KOH on the properties of HA-P-2materials.The results showed that the specific surface area of the 2KHA-P-2-800material at 2 times the amount of KOH was as high as 2417 m²/g,and the material inside Rich in micropores and mesopores,XPS results show that its nitrogen content is 1.57%and phosphorus content is 1.08%.In the three-electrode system,when the current density is 0.5 A/g,it has a specific capacity of 240 F/g,and when the current density is increased to 20 A/g,it still has a specific capacity of 186 F/g.After being assembled into a symmetrical button supercapacitor,the energy density at a power density of 250 W kg^-1 is 7.08 Wh kg^-1,and 97.8%of the capacity remained after10,000 cycles.