The Construction Of Multifunctional Hydrogel Electrolyte And Its Application In Flexible Supercapacitor

With the increasing popularity of flexible wearable devices,the structure and function of flexible energy storage devices are in higher demand.Flexible supercapacitors（FSCs）based on gel electrolytes（GPEs）retain the advantages of traditional supercapacitors（SCs）,such as reversible rapid charge and discharge,high power density,good cycle stability,and at the same time have the advantages of high ionic conductivity,no liquid leakage and flexibility,making them the most promising power sources for wearable devices.It still has great exploration significance for designing GPEs with high mechanical strength,wide temperature range,high self-healing and other comprehensive properties.In this paper,multifunctional GPEs with flexibility were prepared by doping and copolymerization using cheap and easily available polyvinyl alcohol（PVA）and polyacrylamide（PAM）as matrix.The main research contents include:1.Using PVA as polymer matrix,carboxymethyl chitosan（CMCS）as polymer blend material,1-vinyl-3-ethyl imidazolium bromide（[Vi Et Im][Br]）as REDOX active additive,A flexible ultra-thin PVA/CMCS-[Vi Et Im][Br]gel electrolyte membrane with REDOX activity was prepared by blending-coating method.The experimental results show that PVA/CMCS-[Vi Et Im][Br]gel film has good flexibility and mechanical properties.Due to the typical REDOX activity of[Vi Et Im][Br],the FSCS assembled with activated carbon（AC）as electrode material and PVA/CMCS-[Vi Et Im][Br]gel as GPE with thickness of 0.1mm achieved excellent electrochemical performance in acidic media.The energy density can reach 78.6μWh cm^-2,and the capacitance retention rate still reaches 87.5%after 10000 charge-discharge cycles.In addition,PVA/CMCS-[Vi Et Im][Br]gel-based FSC_S still have good electrochemical performance at different bending angles.2.A new kind of flexible PAM/CMCS/PEG-H₂SO₄ gel electrolyte membrane with wide temperature range was prepared by one-step free radical polymerization using PAM as polymer matrix,CMCS as polymer blend material and PEG as functional additive.PAM and CMCS formed hydrogen bond crosslinking network,appropriate amount of PEG added to improve the mechanical properties of the gel,fixed the water molecules.PAM/CMCS/PEG-H₂SO₄ gels exhibit a tensile strain of about 800%,showing good temperature adaptability in the temperature range of-10℃to 90℃.After 5000 cycles of charge and discharge,the capacitance retention rate of flexible devices is 83.3%,showing a good cycle life.In addition,the device exhibits excellent electrochemical performance at various bending angles.3.On the basis of PAM/CMCS/PEG-H₂SO₄ gel,a new self-repairing wide-temperature range PAM/CMCS/PEG/GO-H₂SO₄ gel film was prepared by one-step thermal polymerization by adding GO self-healing function additive.The addition of GO results in higher mechanical strength and toughness（about 900%tensile strain）in the gel.The oxygen-containing groups in GO have excellent self-healing properties through strong interaction with polar small molecules or polymers,and the capacitance remains 92.3%of the original state after 5 cycles of cutting/self-healing.After 6000cycles of charge and discharge,the capacitance retention rate is 83.3%.PAM/CMCS/PEG/GO-H₂SO₄ gel-based SCs showed good temperature adaptability between-10℃and 90℃.In addition,the device shows excellent electrochemical performance at various bending angles,which provides a new way for the preparation of multifunctional hydrogel materials.