Preparation And Electrochemical Properties Of C-PANI-Fe₂O₃ Supercapacitor Anode Materials

Nowadays,energy and environment issues are becoming increasingly serious.Supercapacitors,as an emerging energy storage device,possess the advantages of high capacity and low internal resistance,which in recent years sparked enormous research interests.When a single material is used for the electrode material of the supercapacitor,the properties of the electrode material such as capacitance,cycle,etc,cannot be balanced.So in this thesis,a composite electrode material was prepared by combining carbon materials,polyaniline and iron oxide for high-performance supercapacitors.The carbon materials here include graphene and multi-wall carbon nanotubes,which have characteristics of large porosity,high specific surface area,stable structure,etc.Chemical doped polyaniline provides high conductivity and facile preparation.Moreover,the theoretical capacity of iron oxide is high with low cost.However,they all have their own shortcomings.For example,the carbon materials only have illegal pull capacitors and are prone to agglomeration.Polyaniline and iron oxide,due to redox reaction during charging and discharging,will lead to a volume expansion that destroys the electrode material.Therefore,it is highly expected that the combination of them will hold great promise to achieve the purpose of complementing each other.The preparation of the carbon material/polyaniline/iron oxide composite material can be divided into two steps.Firstly,polyaniline was grown on the carbon material by in-situ polymerization,and then used as a matrix material to grow hollow iron oxide particles on the hollow structure.The as-prepared material has a porous structure,a large specific surface area,and a stable structure.In the preparation process,the relationship between experimental conditions and material structure was investigated by taking the temperature of the hydrothermal reaction,the time,and the concentration of ferrous ions as variables.It is found that in the hydrothermal reaction,the diffusion difference,growth conditions and auxiliary etching of the oxide ions on the surface of the iron oxide crystal all have an effect on the structure of the iron oxide crystal.This topic is to use this principle to realize the ternary composite material.Synthesis of iron oxide hollow particles.Finally,hydrothermal reaction at 180°C for 10 hours gave hollow iron oxide particles with a pore size of 200 nm,and the preparation of the reduced graphene oxide/polyaniline/iron oxide?GPF?composite and multi-walled carbon nanotube/polyaniline/iron oxide?MCPF?composite was completed.After the preparation of the material,the material was heat treated and the electrochemical properties of the material after heat treatment at different temperatures were investigated.The?-Fe₂O₃ in the composite material was transformed into?-Fe₂O₃ after heat treatment,and the performance was greatly improved.After heat treatment,the capacitance of GPF composite increased from 198 F?g^-11 to 457 F?g^-1at 0.5 A?g^-1,while the capacitance of MCPF composite increased from 271 F?g^-11 to 337 F?g^-1at 0.5 A?g^-1.The impedance and cycle stability have been also enhanced.And the heat-treated GPF composite assembled as a supercapacitor delivers a capacitance of 90 F?g^-11 at 0.5 A?g^-1and 64%of capacitance after 5000 charge and discharge cycles.