The Preparation Of Electrode Materials For Chitosan Carbon-based Superacpacitor And Study On Electrochemical Properties

Supercapacitors have been applied in many fields due to their advantages such as short charging and discharging time,long cycle life,environmental protection,high efficiency,little influence by working temperature and no need for manual maintenance.As the energy density and power density of supercapacitors increase,more and more capacitors and batteries will be replaced by supercapacitors.It has been widely used in smart grid systems,electric vehicles,communications,military and aerospace.Supercapacitor electrode materials mainly include carbon materials,metal oxides and conductive polymers.The energy density of carbon electrode is relatively small while that of metal oxide and conductive polymer is high.Starting from carbon materials,metal oxides and conductive polymers,this paper prepares ternary composite materials with carbon materials as the basis of composite metal oxides or conductive polymers.The structure and morphology of composites were studied by means of SEM,TEM,XRD,FT-IR,XPS,BET,etc.and the electrochemical properties of the composites were further studied by means of CV,EIS and cyclic charge-discharge tests,as shown below.Chitosan/polyaniline/manganese dioxide ternary composite was prepared by two-step method.The first step was to grow PANI by in-situ polymerization of chitosan activated carbon（CA）.The second step was to polymerize MnO₂ on the surface of the material by hydrothermal method,and the ternary composite of chitosan/polyaniline/MnO₂ was obtained.Its structure,morphology and composition were characterized by SEM,TEM,XRD,ft-ir,XPS,BET,etc.The results showed that,CA/PANI/MnO₂ composites were coated on the surface of CA by linear PANI molecular chain and nanometer MnO₂ particle load.CA/PANI/MnO₂ composites were presented as mesoporous materials with a specific surface area of 148.2cm²/g by PANI and MnO₂ loading.Electrochemical test results show that the CA/PANI/MnO₂composites exhibited good electrical conductivity,the equivalent series resistance Rs1.26Ω,the charge transfer resistance Rct 0.281Ω.CA/PANI/MnO₂ composites have good stability.The capacitance retention rate of CA/PANI/MnO₂ composites after1000 chargings and discharges is 77.3%.Compared with CA/PANI materials,the capacitance value and capacitance retention rate of composite materials were improved.CA/PANI/Co₃O₄ composites were prepared by one-step method,CA/PANI composites were prepared by co-doping PANI with proton acid H⁺and transition metal ion Co²⁺.On this basis,CoCl₂ was used as cobalt source,and hydrothermal method was used to load and grow Co₃O₄ on CA and PANI surfaces.The composite materials were characterized and the results showed that,Both the PANI molecular chain and Co₃O₄ nanoparticles were distributed on the CA surface.The size of the PANI molecular chain was 0.1μm-10μm,and the particle size of Co₃O₄ was10nm-20nm.The surface of the composite is folded,with an average pore diameter of2.53nm and a specific surface area of up to 481.3 cm²/g,which is a mesoporous material with good pore size structure.The firstⅧCo elements and polyaniline C=C bond in the molecular chain onπelectron cloud some overlap,the micro show the adsorption enhancement,stability,were characterized by XRD,FT-IR on macro characteristic peak position of the mobile.The electrochemical performance test shows that at the scanning speed of 5mV/s,the specific capacitance of the composite is up to 203.7 F/g.After 1000 chargings and discharges,the structural damage degree of PANI molecular chain was significantly reduced compared with CA/PANI,and the capacitance retention rate was 82.6%.