Study On Novel Nitrogenous Heterocyclic Organic Porous Frameworks As Electrode Materials For High Performance Supercapacitors

Owing to the advantages of high power density,long cycle life and environmental friendliness,supercapacitors have become a new type of green energy conversion device which is widely concerned by researchers.At present,the commonly electrode materias used for commercial supercapacitors are mostlly the porous carbon materials,however,the lower spercific capacitance of these electrode materials leads to the undesirable energy density of supercapacitors actually.Therefore,how to improve the specific capacitance of the electrode materials has become one of researching hotspots currently.Studies have shown that heteroatoms-containing porous carbon materials can effectively enhance the specific capacitance of the electrode materials.Nevertheless,the pore structure,types and contents of heteroatoms introduced into electrode materials can not be precisely regulated.Herein,N and O heteroatoms are introduced into the polymer material through covalent bonds,which can improve the specific capacitance of electrode materials and extend the cycle life.In addition,the contents of heteroatoms,pore structure and other microscopic factors could modified via changing the polymerization temperature.Then,the polymerization process is optimized to explore the relationships between the microscopic structure and macroscopic properties of the materials.The specific contents of this paper are as follows:?1?A new monomer THDN containing nitrogenous heterocyclic structure was designed and synthesized.The porous organic polymers PCTFs?Phthalazinone-based Covalent Triazine Frame works?were prepared by ion thermal method at different polymerization temperatures,polymerized at 550°C,600°C,650°C and 700°C,respectively,to obtain PCTFs@550,PCTFs@600,PCTFs@650,PCTFs@700,used as electrode materials of supercapacitor and study its electrical properties.The results show that the PCTFs obtained at different temperatures are dominated by microporous structure accompanying with a small amount of mesoporous structure.With the polymerization temperature increased,the specific surface area of the materials increased from 981 m²/g?PCTFs@550?to 1464 m²/g?PCTFs@700?,and the nitrogen atom decreased from 8.10 at.%?PCTFs@550?to 3.16 at?PCTFs@700?.In a three-electrode test system,the specific capacitance of PCTFs@600 reached 256 F/g at a current density of 0.1 A/g,and the retention of specific capacitance maintained up to 110% after more than 30000 cycles.The energy density of PCTFs@550 was 36 Wh/kg with TEABF4/AN as the electrolyte,and the retention of specific capacitance maintained about 92% after 10000 cycles.?2?On the basis of the PCTFs mentioned above,in order to further improve the ion transport and electrical conductivity of the electrode material,a new monomer BHP,containing phthalazinone structure,and MPCFs?Multi-heteroatoms Porous Carbon Frameworks?were prepared under different polymerization conditions by ion thermal method,to obtain MPCFs@600,MPCFs@650,MPCFs@700,which are used as electrode materials of supercapacitor and study its electrical properties.The results show that MPCFs has more excellent ion transmission and giffueion properties than PCTFs,which is beneficial to the rapid transmission of electrons.Additionly,the pore structure of MPCFs electrode material gradually changed from micropores to mesoporous with the polymerization temperature increased,and the specific surface area and pore volume increased slightly.MPCFs@700 has better capacitance than MPCFs@600 and MPCF@650,and the specific capacitance of 0.1 A/g reached 302 F/g in 1 mol/L H₂SO₄ electrolyte,and the retention of specific capacitance maintained up to 112% after 30000 cycles.The energy density of MPCFs@700 was up to 65 Wh/kg with [BMIM][BF4] as the electrolyte,and the retention of specific capacitance maintained about 98% after 10000 cycles.