Design And Preparation Of Stretchable Conductive Hydrogels And Its Application In Energy Storage Devices

Conductive hydrogels have attracted extensive attention due to their tunability of electrical and mechanical properties,it is also a novel flexible electrode material that combines electrical conductivity with the porous water-absorbing properties of hydrogels.However,the existing PEDOT:PSS hydrogels are generally prepared by mixing electroactive fillers into insulating polymer matrices,which inevitably reduces its electrical properties while obtaining better mechanical flexibility.Based on this,this thesis is devoted to developing conductive hydrogel electrode materials with high conductivity and mechanical flexibility and exploring new fabrication processes for supercapacitors.Therefore,it can adapt to and promote the development of flexible energy storage technology.The main contents of the research include the cooperative regulation of high conductivity and mechanical flexibility of conductive hydrogels,electrode preparation,performance characterization and device application.The main work are as follows:1.A highly conductive hydrogel with intrinsic stretchability was designed.In view of the existing problem that it is difficult to realize the high conductivity and mechanical flexibility of conductive hydrogels simultaneously,an effective synergistic regulation strategy was proposed to construct free-standing PEDOT:PSS hydrogels,simultaneously showing ultra-high conductivity(～3000 S m^-1)and superior stretchability（～55%）,by adding the pristine PEDOT:PSS solution with both conductive enhancer（DMSO）and plasticizer（Triton X-100）followed by thermal treatment without using insulating polymer matrixes.In addition,the prepared conductive hydrogel possess high resilience,low Young’s modulus,excellent swelling properties and 3D printing suitability.Moreover,substrate-free highly elastic all-gel SCs were fabricated using the resulting PEDOT:PSS hydrogels as electrodes and PVA-H₃PO₄ gel as electrolyte.The free-standing SCs demonstrated simple device structure with fewest layers and facile assembly procedures.Also,they exhibited very high areal specific capacitance(the optimum value of～177 m F cm^-2),excellent energy storage capacity(energy density of～15.76μWh cm^-2,power density of 400μW cm^-2).This work provides a new reference for the development of electrode materials of flexible energy storage devices in the future,and expands the possibility of large-scale industrialization and wide application of flexible electronics.2.A preparation scheme of stretchable linear total gel supercapacitor was proposed.In view of the shortcomings of thin film energy storage devices mentioned in the previous chapter,such as large body,heavy weight,inflexible and difficult to integrate,a stretchable fibrous hydrogel electrode was proposed to inherently stretchable linear all-gel supercapacitor,simultaneously showing excellent electrochemical performance(～1120 m F g^-1),intrinsic tensile（～78%）,excellent cycle stability（Retain the capacitance retention of～80%afrer 1000 charging cycles）,stable performance（Retain the capacitance retention of～75%at 30%tension）,enable arbitrary deformation and weaving.The excellent performance is mainly owing to the mutual induction of PEDOT by EG and Triton X-100 to form interchain interconnections and entanglements.Moreover,it is different with traditional linear supercapacitors,which require active material to be deposited on a flexible substrate,all-gel SCs do not require additional substrates,which reduces device mass while increasing electrochemical activity.The exceptional electrochemical performances,facile assembly,simple structure together with excellent deformability make the intrinsically stretchable linear all-gel SCs ideal for flexible/wearable electronics.