Capacitance Properties Of Metal-Organic Frameworks(MOFs) And Their Derivatives

Supercapacitors(SCs),as one of the promising energy storage devices,have attracted increasing attention due to the high power density and long cycle life.Flexible solid-state supercapacitors(SSCs)has boomed in recent years in order to meet the rapid growing demand for portable electronic devices because of their exceptionally long cycle life,lightweight,ease of handling,flexible,safety and high power density.However,the energy density of SCs is too low to limit their applications.Considering this problem,developing new materials to address these defects is a key part to improve the performances of SCs.Metal organic framework materials(MOFs)are crystalline materials composed of metal ions(or metal clusters)and organic linkers.As a novel class of porous materials,MOFs have attracted great attention in recent years owing to their high surface area,tunable chemical composition,tunable pore size,controllable functional ligands and open metal sites.More recently,MOFs have been successfully used as electrode materials for rechargeable batteries and fuel cells because the redox behavior of metal cations inside MOFs provides a pathway for electrons,and the linker structure promotes charge transfer inside the framework.In this work,we attempted two methods to solve the MOFs as the electrode material but nonconductive.One is through the addition of nitrogen-containing ligands(adenine)in UiO-66,followed by carbonization at different temperatures to prepare nitrogen-doped porous carbon(NPC);Another route to enhance the capacitance of electrode materials is through electrochemically deposited pyrrole on different sizes of ZIF-8.The synthesized hybrid electrode materials were characterized and tested by a variety of analytical methods(e.g.TG?XRD?XPS,etc).Electrochemical studies show that either carbonized or composited with other conductive materials,the electrode mateials showed an excellent electrochemical performance.This indicates that the MOFs conductivity can be significantly improved by these two mathods.we also assembled and tested a symmetrical flexible solid-state supercapacitors,electrochemical tests show that the device not only has excellent electrochemical properties,but also has excellent mechanical stability and cycle stability.