Research On The Preparation And Performance Of A Heteroatomdoped Electrode Material For Supercapacitors With Organic Ligands As The Precursors

Supercapacitor,as a new kind of clean energy storage device,occupies an important position in the field of storage with its fast charge and discharge as well as the advantage of a high safety performance and a long service life.Carbon materials have been a focus of research on the electrode materials of supercapacitors due to their advantages including stable chemical properties,a high conductivity and a high specific surface areas area,etc.However,carbon materials also have disadvantages includ-ing a smaller specific capacitance and a low energy density,and those pre-pared with natural materials have disadvantages including unstable raw material sources and a low reproducibility.In addition,the production cost of high-performance carbon materials(such as CF and CNT)is very high,the process is complex and the subsequent processing is difficult,which greatly limits their wide application.Therefore,in order to obtain carbon materials with a stable structure,a good repeatability,a sufficient raw ma-terials and a large-scale industrial production,heterocyclic organic ligands with high carbon content were selected as precursors in this papar,whose structure was adjusted and optimized through high temperature carboniza-tion,alkali activation,coordination with metal ions,doping heteroatoms and other methods,so as to prepare electrode materials with a high electro-chemical performance.The detailed research work is as follows.(1)An organic ligand 4-(2,4,6-tricarboxylphenyl)-2,2,6,2'-terpyridine-terpyridine containing carboxyl groups and a heterocyclic ligand 2,6-bis(2-pyrazinyl)-4-(4-(tetrazol-5-yl)phenyl)pyridine containing nitrogen were used as the carbon precursors.Then,under a nitrogen atmosphere,two nitrogen-doped carbon materials,namely A-700 and Z-700,were obtained after carbonation at 700?,both of whose electrochemical properties were tested,and the results were satisfactory.(2)Activated by KOH,a terpyridine ligand 4-(2,4,6-tricarboxylphenyl)-2,2,6,2'-terpyridine and a heterocyclic ligand 2,6-bis(2-pyrazinyl)-4-(4-(tetrazol-5-yl)phenyl)pyridine containing nitrogen respectively underwent complexing reactions with transition metals like Zn or Fe salt directly.The coordination compounds obtained were subsequently carbonized at a high temperature under a nitrogen atmosphere,obtaining corresponding A/Zn-700 and A/Fe-700 doped with carbon materials.Both materials have a rich porous structure and a large specific surface areas area,which lead them to show an excellent electrochemical performance.The experimental results show that at 0.5 A/g,the specific capacitance of A/Zn-700 is 297.5 F/g and the energy density is 61.5 Wh/Kg,and the specific capacitance of Z/-700 is 300.4 F/g.(3)In order to obtain carbon materials with more outstanding electrochemical properties,other heteroatoms(B,N or P)were introduced in the metal-organic coordination compounds activated by KOH,so as to prepare carbon materials with a high doping content,namely C/B-700 and C/P-700.Physical characterization showed that the N,B and O atoms doped in C/B-700 or N,P and O in C/P-700 were evenly distributed within the materials,all of which were of a porous structure,and the specific surface area of C/B-700was as high as 2855.3901 m~2/g through a test.Finally,according to the test results,both materials exhibited excellent electrochemical properties.The C/B-700 shows a high specific capacitance of 422.3F/g and a high energy density of 83.0 Wh/Kg,the specific capacitance of C/P-700 is 363.2 F/g,and C/P-700 shows a high rate performance(capacitance retention rate is 60.5%at 10A/g)together with a long service life.It is found in the test that both materials have great practical values.