MOFs And Their Derivatives As Electrode Materials For Supercapacitors

Since the industrial revolution,the invention and application of various machines have greatly improved people’s lives,but driving machines requires a lot of energy,so the massive use of fossil energy sources such as coal,oil and natural gas is inevitable.Nowadays,with the increasing depletion of energy sources and the environmental degradation caused by burning fossil energy sources,the development and utilization of new clean and renewable energy sources have received widespread attention.Accordingly,new energy storage devices such as supercapacitors have been developed.In this paper,metal organic frameworks（MOFs）and their derivatives are used as supercapacitor electrode materials.The research in this paper is divided into three parts as follows.（1）Preparation and electrochemical properties of copper-based MOFs HKUST-1 and its derived metal sulfide Cu₉S₅.Firstly,HKUST-1 was prepared by hydrothermal method as a precursor material and sodium sulfide（Na₂S）as a sulfur source,and the effects of different reaction temperatures on the electrochemical properties of the prepared products were investigated.The crystalline properties,morphology,pore structure and elemental valence of the prepared electrode materials were characterized by XRD,SEM,XPS,FT-IR,BET and BJH techniques.It was found by experimental tests that the Cu₉S₅prepared at120°C has excellent electrochemical properties.The electrochemical properties of Cu₉S₅prepared at 120°C were further explored,and the multiplicative performance and stability of the Cu₉S₅electrode material prepared at the mass ratio of MOFs material to Na₂S of 1:2due to other groups.（2）Preparation of iron-based MOFs MIL-88（Fe）and its derived ferrous disulfide（Fe S₂）and study of their electrochemical properties.The MOFs MIL-88（Fe）were prepared by hydrothermal method,and the electrochemical properties of Fe S₂obtained by vulcanization with different ratios of thioacetamide（TAA）were investigated.The crystalline properties,morphology,pore structure and elemental valence of the synthesized materials were characterized by XRD,SEM,XPS,FT-IR,BET and BJH.The experimental results show that the obtained electrode materials exhibit the highest specific capacity when the mass ratio of added TAA to MOF is 2:1.The rate performance and cycling stability obtained with a TAA to MOF ratio of 2:1 were superior to the other groups by charge/discharge tests and long cycle stability tests.（3）Preparation of nickel-based MOFs[Ni（Tdc）（Bpy）]n and study of their electrochemical properties.The reaction of 2,5-thiophene dicarboxylate（Tdc）and 4,4’-bipyridine（Bpy）ligands with nickel salts was used to prepare[Ni（Tdc）（Bpy）]n.The effects of different kinds of nickel salts and the reaction temperature on the electrochemical properties of the reaction products were investigated.The crystalline properties,morphology,pore structure and elemental valence of the prepared electrode materials were also characterized by XRD,SEM,XPS,FT-IR,BET and BJH techniques.The experiments showed that the prepared MOFs materials have high specific capacity at the reaction temperature of 60°C.The specific capacity,rate performance and cycling stability of the MOFs based electrode materials prepared by nickel sulfate as nickel salt were found to be excellent.759 F g^-1specific capacity was achieved at a current density of 0.5 A g^-1.