Studies On Properties Of Materials Based On Metal-organic Frameworks And Biomass Carbon For Supercapacitor

The high-performance electrochemical energy storage devices need to be developed to solve the contradiction between environment and energy due to the increasing irreversible consumption of fossil energy.Supercapacitors with high power density,fast charge/discharge process and long cycle life have great development prospects.Given the electrode materials largely determine the electrochemical properties,this work mainly researches two kinds of capacitor energy storage materials including metal organic frameworks(MOF)material and biomass carbon material.The research contents are as follows:(1)Ni-MOF was synthesized by hydrothermal method at 120 °C,and the morphology and structure of Ni-MOF were characterized by adjusting the metal source and ligand reaction ratio.Furthermore,structure-function relationship between the structure and properties of Ni-MOF was explored through the result of the electrochemical performance test.According to the result of test,it was found that all of the Ni-MOF showed nanosheet-like stacked morphology.Electrochemical performance tests showed that the MOF with a reaction ratio of 1.5:1 revealed the best performance.In 3 M KOH electrolyte,the specific capacitance of 905 F/g and580 F/g can be achieved at the current density of 0.25 A/g and 10 A/g.According to assembling the asymmetric capacitor,the highest energy density and power density can achieve 19.93 Wh/kg and 3750 W/kg,respectively.The analysis of the reaction kinetics of the material showed that the redox process of Ni-MOF was a typical charge storage mechanism controlled by the diffusion process.(2)Rhizobium used as the precursor was activated by KOH chemical activation method,and the morphology and electrochemical properties of activated carbon were characterized at different activation temperatures.Ultimately,the activated carbon and glucose were co-carbonized to optimize the capacitance performance of the activated carbon.Electrochemical tests showed that the capacitance performance of rhizobia-based activated carbon was the best at 700 ?.At a rate of 1 A/g,the specific capacitance of the material was 222 F/g.Even at a rate of 10 A/g,the specific capacity of the material was 170 F/g with the capacity retention rate of 76.5 %.After co-carbonizing the 700 ? activated rhizobium and glucose at a mass ratio of 2:1,5:1,10:1 and 20:1,the capacitance performance of the electrode material with a mass ratio of 10:1 was the most outstanding.The specific capacitance of 343 F/g and 231.8 F/g can be reached at the current densities of 1 A/g and 10 A/g,respectively.The energy density was 12.91 Wh/kg.At a current density of 2 A/g,99.5 % performance was retained after 10000 cycles.These excellent performances indicated that the introduction of glucose improving the effective charge storage space to increase the specific capacitance of activated carbon.