Preparation Of Metal Hydroxide/graphite Fiber Flexible Electrode And Research On Capacitance Performance

With the excessive exploitation and use of non-renewable resources such as oil and coal,the problems of energy exhaustion and environmental pollution are getting more and more serious,forcing the development of new renewable energy sources and increasing demand for energy storage devices that can store and convert energy.As one of the promising energy storage devices,supercapacitors have the advantages of high power density,strong environmental adaptability,long charging cycle life,fast charging speed and high safety and stability,but they are limited by the problem of low energy density.As a result of the formula"E=1/2 CV~2",the specific capacitance and operating voltage range of electrode materials are important to increase the energy density of supercapacitors.In this paper,we use electrochemical modified graphite fibers(GFs)as the substrate to load transition metal hydroxide with high specific capacitance as the positive and negative electrodes of asymmetric supercapacitors,so as to construct fiber supercapacitors with high energy density and excellent rate capability.Details are as follow:1.Graphite fiber was selected as the substrate material.Firstly,the surface electrochemical modification of graphite fiber was carried out in the mixed acid of concentrated sulfuric acid and concentrated nitric acid.After that,the surface of electrochemical activation graphite fibers(EAGFs)became rough,the surface area increased,and the hydrophilicity was improved.Moreover,EAGFs successfully introduced oxygen-containing groups to improve the electrochemical performance of graphite fiber.2.In order to increase the energy density of electrode materials,we used an efficient and environmentally friendly electrochemical deposition method to rapidly complete the composition of EAGFs and transition metal hydroxides in a short time,that is,NiCo-layered bimetallic hydroxide(LDH)nanosheet and FeOOH nanosheets were electrodeposited on EAGFs to synthesize positive electrode materials(NiCo-LDH/EAGFs)and negative electrode materials(FeOOH/EAGFs).The electrochemical modification increases the load of active substances and promotes the formation of C-O-Metal bonding,so the EAGFs can bond firmly to NiCo-LDH and FeOOH,which helps establish fast electron transport routes and ion transport channels.Both NiCo-LDH and FeOOH anchored on EAGFs display a high rate performance.3.In addition,the flexible solid supercapacitor assembled by positive electrode material NiCo-LDH/EAGFs and negative electrode material FeOOH/EAGFs has the advantages of high capacitance,excellent rate performance,good cyclic stability and high energy density,which provides a new idea for the preparation of flexible asymmetric supercapacitor.