Preparation And Property Study Of Flexible Supercapacitor Based On Polyvinyl Alcohol/Carbon Nanotube Composites

The supercapacitors have attracted much attention due to their fast charging and discharging,good cycle stability,high power density and environmental friendliness.With the emerging of flexible electronic products and wearable devices,great attention has been paid to the research and optimization of flexible supercapacitors,which are highly flexible,foldable,stretchable and other characteristics.How to improve the mechanical properties and cyclic stability of the supercapacitors without sacrificing capacitance has become research focus.The key is to prepare high performance flexible electrode materials.Polyvinyl alcohol?PVA?,as a highly flexible material,has stable physical and chemical properties,economic and environmental protection,and is easy to form films.Carbon nanotubes?CNT?,have excellent electrical and mechanical properties.In this thesis,based on the characteristics of CNT and PVA,the CNT/PVA based composite film with good electrical conductivity and independent properties was obtained and applied as flexible symmetrical electrodes in supercapacitors.The main researches are shown as follows:1.With PVA as raw material,it is easy to dissolve in water at elevated temperature and form films.The PVA/CNT flexible films were prepared by mechanical mixing with CNTs.The films as electrode showed excellent flexibility and electrochemical properties.The specific capacitance of the electrochemical test was 16.5 mF/cm².2.In order to improve the capacitive properties of PVA/CNT film,CNTs were modified by one-step hydrothermal method to combine with nickel bicarbonate?Ni?HCO₃?₂?.The PVA/CNT@Ni?HCO₃?₂ based flexible supercapacitor achieved an specific capacitance of 114 mF/cm²,showing excellent capacitance performance at different bending angles and stretching states.3.Flexible electrode materials with high specific capacitance and stability were further prepared,and polyaniline?PANI?was oxidized in-situ on PVA/CNT films using ammonium persulfate?APS?as oxidant,the PVA/CNT/PANI composite films were used as electrodes to assemble a flexible solid-state supercapacitor and achieved an specific capacitance of 196.5 mF/cm².