Preparation And Properties Of Cathode Materials For Fibrous Zinc Ion Hybrid Supercapacitor

Fiber supercapacitor（FSC）has attracted much attention because of its advantages such as high power density and long cycle life,but it has the problem of low energy density.In this thesis,based on the design idea that hybrid capacitor can have both high energy density and high power density,a flexible fiber-shaped electrode reinforced by pseudocapacitor material is prepared and assembled into quasi-solid flexible fiber-shaped zinc ion hybrid supercapacitor（QFFZIHSC）.In the experiment,flexible carbon fiber yarn（CFY）and stainless steel wire（SSY）were selected as current collectors respectively,and conductive polymers and metal oxides were prepared in-situ on the surface of current collectors by electrochemical deposition and hydrothermal method.The structures and properties of the prepared electrodes and devices were analyzed.The main contents of this paper are as follows:（1）LiV₄O₁₀·1.8H₂O was coated on carbon fiber yarn to form CFY@LiV₄O₁₀·1.8H₂O electrode by hydrothermal method.and the effects of hydrothermal time on the morphology and electrochemical performance of the electrode were studied.The results show that the hydrothermal time is 6 hour,and the LHV-6 electrode has the best electrochemical performance.QFFZIHSC was assembled by using LHV-6 electrode as positive electrode,the carbon fiber yarn with Zn electrochemically deposited on its surface as the negative electrode（CFY@Zn）and polyacrylamide/Zn SO₄（PAM/Zn SO₄）gel as electrolyte,and the voltage window of the capacitor was 0-1.5 V.The capacitor exhibits a maximum specific capacity of2.20 m Ah/cm²,the maximum energy density of 1.65 m Wh/cm,the capacity retention rate of 85.9%after 1000 charge/discharge cycles and capacity retention rate of 84.5%after 2000 bending cycles.（2）The steel wire yarn@polypyrrole（SSY@PPy）electrode was prepared by potentiostatic chemical deposition method,and the effects of electrochemical deposition time on the morphology and electrochemical performance of PPy electrode were studied.The results show that the deposition time is 70 min at 1.5 V constant voltaget,and the SSY@PPy-70 electrode has the best electrochemical performance.QFFZIHSC was assembled by using SSY@PPy-70 electrode as positive electrode,Zn wire as negative electrode and gelatin/Zn SO₄gel as electrolyte,and the voltage window of the capacitor was 0-1.8 V.The capacitor exhibits a maximum specific capacity of 43 m Ah/g,the maximum energy density of 38.7 Wh/kg,the capacity retention rate of 83%after 1000 charge/discharge cycles and capacity retention rate of88.4%after 1000 bending cycles.（3）Poly 4-aminophenol（PPAP）and poly 3,4-ethylenedioxythiophene（PEDOT）was coated on carbon fiber yarn to form CFY@PEDOT@PPAP electrode by two-step electrochemical deposition method.The effects of PEDOT with different deposition time on the electrochemical performance of the electrode were studied.The results show that the best electrochemical deposition time of PEDOT is 16 min,and the CFY@PEDOT@PPAP-16 electrode has the best electrochemical performance.QFFZIHSC was assembled by using CFY@PEDOT@PPAP-16 electrode as positive electrode,CFY@Zn as negative electrode and PAM/Zn SO₄gel as electrolyte,and and the voltage window of the capacitor was 0-1.8 V.The capacitor exhibits a maximum specific capacity of 222.9 m Ah/g,the maximum energy density of 180.5 Wh/kg,the capacity retention rate of 54%after 3000 charge/discharge cycles and capacity retention rate of 60.40%after 3000 bending cycles.