Preparation And Electrochemical Capacitance Of Porous Carbon-metal Organic Framework Composites

As human demand for sustainable and renewable energy sources increases,supercapacitors enter the field of vision as a new type of energy storage device.Supercapacitors have higher power density than batteries,and have higher specific capacitance and energy density than conventional capacitors,long cycle life,high reversibility,and no pollution to the environment.Research and exploration of new high-performance supercapacitor electrode materials is a research hotspot in the field of chemical materials and the environment.In this thesis,the preparation of a novel porous carbon-metal organic framework composite is proposed,and its capacitance performance is studied in order to provide a new idea for the development of electrode materials with high capacity,excellent cycle and rate performance.The main work carried out is as follows:（1）The preparation of porous carbon and the study of its capacitance properties were carried out.Porous carbon was used as carbon source to prepare porous carbon with high specific surface area by foaming method.The effects of dopamine induction,heating mode and melamine doping on the morphology,element composition,structure,specific surface area and electrical conductivity of porous carbon were studied.And study its electrochemical capacitance performance.Studies have found that the addition of dopamine in an appropriate amount affects the condensation and polymerization of glucose and can be better matched to the decomposition of ammonium salts.As the dopamine content increases,the specific surface area（SSA）of the porous carbon increases first and then decreases.The maximum SSA of porous carbon produced with5%dopamine can reach 2621 m²/g and exhibits maximum electrochemical performance with a specific capacitance of 96.7 F/g.At a high current density of 10 A/g,the capacitance remains.The rate is 80%and has good cycle performance.The heating mode with constant temperature and melamine doping can effectively improve the graphitization degree and conductivity of porous carbon.（2）The preparation and capacitance properties of porous carbon-metal organic framework composites were carried out.Two kinds of Ni-based MOFs were selected as research objects,and the metal organic framework crystals were grown in the pores of porous carbon by direct hydrothermal method to obtain a porous carbon-metal organic framework composite.It was found that two metal organic framework compounds,Ni₃（HCOOH）₆ and Ni-BDC,were successfully grown in porous carbon.The experimental results show that the porous carbon-Ni₃（HCOOH）₆ composite has better capacitance performance than the porous carbon-Ni-BDC composite.At a concentration of 40 mmol of Ni₃（HCOOH）₆ precursor solution,a composite with a specific capacitance of 313.8 F/g was obtained.At a concentration of 10 mmol of Ni₃（HCOOH）₆precursor solution,a composite with a conductivity of 57.15 S/m was obtained.It is proved that the specific surface area and specific capacitance of the composite can be adjusted by controlling the concentration of the precursor compound solution of the metal organic framework compound.Compared to porous carbon,the composite has a higher specific capacitance and electrical conductivity..