The Application Of Metal Organic Frameworks For Supercapacitors

The supercapacitor （ESs） is a new type electrochemical energy storage devicebetween the traditional dielectric capacitor and the battery. ESs have attracted increasedinterest due to their higher power density and long cycle life than batteries, so ESs areregarded as ideal energy storage devices to meet in mobile telecommunication, informationtechnology, consumer electronics, aerospace, backup energy sources, and so on. Accordingto the principle of energy-storage there are two types of supercapacitors: electricdouble-layer capacitor （EDLC） and faradaic pseudocapacitor, electrical double-layercapacitor with activated carbon materials as electrodes, and the other is Faradicpseudo-capacitor with metal oxides or conducting polymers as electrodes. The elementarystructure of a supercapacitor is composed of electrode, electrolyte, current collector, and soon. The capacitor properties of the ESs are closed related with the electrode and electrolyte,so it is indispensable to develop an advanced supercapacitor device. Metal organicframeworks （MOFs） are new functional materials that combine a wide variety of propertiesand applications. They contain inorganic and organic networks that can be easilyfunctionalised to get tuneable properties. They are commonly used in sensing, catalysis,ion exchange, separations or gas storage, and as electrode material for lithium ion battery.They are also used as a template for syntheses of nanoporous carbons as electrodematerials for supercapacitor. In this paper, A series of Metal-Organic Frameworks weresuccessfully synthesized for the first time used as electrode materials for supercapacitor.The samples were examined by X-ray diffraction （XRD）, transition electron microscopy（TEM） and N2adsorption/desorption isotherms. Capacitor properties of the samples werecharacterized by cyclic voltammetry （CV） and electrochemical impedance spectroscopy（EIS）. The main results and innovations are as follows:（1） A series of Metal-Organic Frameworks based on isonicotinic acid and nickel nitratewere successfully synthesized by a solvothermal method as electrode materials for thefirst time used as electrode materials for supercapacitor. The maximum specificcapacitance is found to be634F g^-1at5mV s^-1and the stable cycling propertiesmeasurement showed the sample kept84%after2000cycles at a50mV s1scan rate.（2） A series of Metal-Organic Frameworks based on1,3,5-benzenetricarboxylic （BTC） acid and M（II） acetate hydrate （M=Co, Ni, and Zn） were successfully synthesized andnamed as M₃（BTC）₂·12H₂O, The maximum specific capacitance of Ni₃（BTC）₂·12H₂Ois found to be429F g^-1at5mV s^-1and154F g^-1at200mV s1scan rate.（3） A series of Metal-Organic Frameworks of Nickel4-pyridine carboxylate tetrahydratewere successfully synthesized, The maximum specific capacitance is found to be1149F g^-1at5mV s^-1.（4） A series of Metal-Organic Frameworks as electrode materials for supercapacitor forfirst time.