Study On Construction Of High-capacitance Conducting Polymer Hydrogel And Its Energy Storage Mechanism

Continuous progress in wearable electronics boosts the development in light,thin and flexible supercapacitors.However,the energy density of flexible supercapacitors are far from the level of the requirements of flexible electronics.It is an effective solution to solving this problem by designing and preparing high specific capacitor electrode materials with excellent mechanical properties.In this paper,polyaniline/polyvinyl alcohol（PANI/PVA）conducting polymer hydrogels were fabricated by freezing-thawing cycles.A series of motheds were applied to improve the electrochemical performance of PANI/PVA hydrogel electrodes.The main work is as follows:（1）In a homogeneous solution of aniline and polyvinyl alcohol,the self-standing PANI/PVA conducting hydrogel was prepared by in-situ polymerization of aniline in which phytic acid acted as dopant.Soft polyvinyl alcohol chain brings hydrogel well flexibility,and the polyaniline inter-molecular doped by phytic acid forms an efficient electronic transport network.As a result,PANI/PVA hydrogel exhibits excellent conductivity and electrochemical performance.0.3 M PANI/PVA hydrogel electrode delivers high electrochemical capacitance(842 m F cm^-2at 1 m A cm^-2).After 10000cycles,the hydrogel electrode shows 78.2%capacitance retention.Based on 0.3 M PANI/PVA hydrogel electrode,an all-hydrogel-state supercapacitor is assembled.The supercapacitor demonstrates energy density of 17μWh cm^-2at 250μW cm^-2.（2）Hydroquinone-modified conducting polyaniline hydrogel（PANI/HQ/PVA）was prepared by introducing hydroquinone as redox additive.During the process of Charge/Discharge,electrons are stored through benzoquinone/hydroquinone transition.Area specific capacitance of the PANI/PVA hydrogel electrode is improved by synergistic effect of HQ and PANI.As a result,hydrogel electrode delivers high electrochemical capacitance of 1267 m F cm^-2at HQ molarity of 10 mmol L^-1.PANI/HQ/PVA hydrogel electrode shows 93%of initial capacitance retention after repeated bending 500 cycles.After 10000 cycles,the hydrogel electrode shows 81.5%capacitance retention.Based on PANI/HQ/PVA-10 hydrogel electrode,an all-hydrogel-state supercapacitor is assembled.The supercapacitor demonstrates energy density of 23.64μWh cm^-2and remains 88.2%of initial capacitance retention after bending 180°.（3）PANI/PVA conducting hydrogel electrode using Na Cl as soft template（PANI/PVA-Na Cl）was prepared.As a result,PANI/PVA-Na Cl hydrogel electrode exhibits high specific capacitance(1544 m F cm^-2at 1 m A cm^-2).After repeated bending 500 cycles,PANI/PVA-Na Cl hydrogel electrode shows 92%of initial capacitance retention.After 10000 cycles,the hydrogel electrode shows 84%capacitance retention.A flexbile supercapacitor was assembled which demonstrates energy density of 51.1μWh cm^-2.（4）Co-doping PANI/PVA conducting hydrogel electrode was prepared by using sulfuric acid and phytic acid as dopant.When molarity of H₂SO₄:PA is 1:2,the hydrogel electrode exhibits high conductivity(18.9 S m^-1)and specific capacitance(1697 m F cm^-2).After 10000 cycles,the hydrogel electrode shows 82%capacitance retention.Based on this hydrogel electrode,an all-hydrogel-state flexbile supercapacitor is assembled which demonstrates energy density of 52.2μWh cm^-2.The supercapacitor remains 92.2%of initial capacitance retention after bending 180°.