Preparation Of Self-healable Polyelectrolytes And Their Applications In Supercapacitors

Wearable devices recently are more and more widely used.As a result,flexible energy storage devices have been inseparable from daily life.Traditional energy storage devices are prone to be demaged or even fail suffering from the superposition of various external stresses such as temperature,pressure,humidity and mechanical deformation like bending,stretching and twisting.Herein,a self-healing polyelectrolyte was developed in order to improve the reliability of energy storage devices,especially the supercapacitors.A hydrogel electrolyte with excellent mechanical properties and desirable ion conductivity was prepared by high-density multiple Hydrogen bonds of polyvinyl alcohol?PVA?and poly?2-acrylamido-2-methyl-1-propanesulfonic acid??PAMPSA?.Polypyrrole-coated single-wall carbon nanotube film electrodes were prepared by in situ polymerization of pyrrole monomers on carbon nanotubes to construct a self-healing symmetric supercapacitor with sandwich structure.Then,a printable Poly?3,4-ethylenedioxythiophene??PEDOT?hydrogel was prepared.The hydrodel electrode was printed as interdigital pattern onto structured polyelectrolyte assembled into a self-healing micro supercapacitor eventually.The electrochemical performance and self-healing properties of polyelectrolytes were investigated.The hydrogel polyelectrolyte prepared facilely exhibited superior transparency,excellent mechanical properties?938%of breaking strain and 112.68 kPa of breaking stress,respectively?and high ionic conductivity(20.6 mS·cm^-1).Moreover,the prepared polyelectrolyte processed a significantly improved mechanical properties compared to pure PAMPSA.The breaking stress increased first and then decreased with increasing PVA content and reached maximum stress?112.68 kPa?at 8 wt%PVA content.The breaking strain increases with increasing PVA content and achieved maximum strain?938%?at 10 wt%PVA content.The self-healing ability of mechanical properties of polyelectrolyte first increased and then decreased with the increase of PVA content.Maximum of healing efficiency was obtained at 6 wt%PVA?92.68%for breaking strain and 88.06%for breaking stress?.The polyelectrolyte processed a fast and multiple self-healing ability for mechanical properties at room temperature.Furthermore,excellent self-healing ability for electrochemical performance of the polyelectrolyte was impressive at room temperature.In self-healing process,the initial resistance was restored in 40 minutes.Besides,resistance of polyelectrolyte substantially maintained invariable after 10 cut/self-healing cycles.Electrochemical performance and self-healing property of self-healing flat symmetrical supercapacitors were investigated.The supercapacitor can recover the original impedance after 10 cutting/self-healing cycles.Supercapacitors have excellent areal specific capacitance?C_s?and rate performance.At a current density of 5 mA cm^-2,the C_s reaches 218 mF cm^-2.After self-healing,the electrochemical performance is almost completely restored.The area specific capacitance of the supercapacitor before self-healing is 258 mF cm^-2.The C_s after self-healing is 256 mF cm^-2,and the healing efficiency is 99.2%(current density 1 mA cm^-2).Moreover,the supercapacitor has excellent coulombic efficiency before and after self-healing,and the coulombic efficiency is 90.57%before self-healing and 85.20%after self-healing.Performance studies of on printable PEDOT gels were performed.The gel with120 mg/2g PEDOT solution addition content was selected as the gel electrode.This gel exhibited the viscosity of 546 Pa·s and the conductivity of 1.15 S m^-1 processing desirable comprehensive performance.Electrochemical and self-healing performance of self-healable micro supercapacitors were investigated.The micro supercapacitor fabricated by printing the gel electrode on a polyelectrolyte substrate processed superior C_s and excellent rate performance.At an current density of 2 mA cm^-2,the C_s reached 43 mF cm^-2.The healing efficiency of C_s and ESR of micro supercapacitor was78.9%and 97.3%,respectively.