Preparation Of MOFs-derived Hierarchical Porous Carbon And Study On Its Supercapacitor Performance

In recent years,electric double layer supercapacitors(EDLC)have good application prospects in electrochemical energy storage and new energy vehicles.The huge specific surface area and graded pore size distribution of carbon-based materials have been a hot spot in the field of capacitors for decades.Carbon materials derived from metal organic frameworks(MOFs)are considered a very promising type of porous carbon materials in the near future.By using MOFs as precursors,porous carbon materials with adjustable pore size and high specific surface area can be obtained.Most of the current research is devoted to the development of new MOF-derived carbon materials.This thesis aims to explore the influence of the regulation of MOF precursors on the performance of porous carbon capacitors based on the synthesis of new carbon materials.The work contents of the thesis are as follows:(1)Al-BTC synthesized with Al and 1,3,5-benzenetricarboxylic acid under mild hydrothermal conditions,after high-temperature carbonization and alkaline washing steps,obtained hexagonal nano-disc porous carbon(HPCN),Al-BTC’s unique hexagonal disc structure makes it have a highly stable structure before and after carbonization.HPCN has a huge specific surface area of 2123 m2g-1.And HPCN can shows 297 F g-1 at 1 A g’1.In the ultra-long charge-discharge cycle of 200,000 times,the decay rate of HPCN is only 5.4%,which reflects a good cycle life.In addition,by adjusting the concentration of metal ions,the particle size of the MOF is controlled,and the porosity of the porous carbon material is changed,thereby optimizing the capacitance performance.(2)A new type of spindle-shaped porous carbon material(RPC)derived from Al-BTEC was prepared based on a green approach.RPC has a good hierarchical porous structure.It exhibits a specific surface area of 1895 m2 g-1 and an average pore size of 2.3nm in the nitrogen absorption and desorption test.The pore size distribution is very suitable for the storage and rapid transfer of electrolyte ions between the pores.Electrochemical test results show that RPC can display a discharge specific capacitance of up to 334 F g-1,and it can also contribute 213 F g-1 at a high current of 100 A g-1,showing excellent capacitance performance.In addition,by comparing with HPCN,it can be found that the special coordination mode of Al-BTEC is beneficial to the formation of larger pore size,and the influence of the coordination mode of the MOF precursor on the performance of the graded porous carbon capacitor is analyzed.(3)Bimetal MOF-derived porous carbon(ARPC)was prepared by doping Al-MOF with Zn.In order to solve the problem of poor performance of Al-MOF-derived carbon ratio,the Al/Zn bimetallic MOF was obtained by introducing Zn2+to participate in the coordination of MOF without using chemical activation.Due to the introduction and reduction of Zn,hierarchical porous carbon with a mesoporous area of 878 m2 g’1 and a specific surface area of 1400 m2 g’1 was obtained.RPC has shown excellent performance in electrochemical tests.It can have specific capacitance values of 361 and 283 F g-1 in 1 and 100 A g-1 charging and discharging tests,and it can have a specific capacitance of 375 and 283 F g-1 in a long-term cycle test of 150,000 times.The cycle retention rate of 96.2%reflects the bimetallic synergistic effect of Al and Zn,and provides a new idea for the synthesis of hierarchical porous carbon.