Preparation And Properties Of Gel State Flexible Supercapacitor

With the rapid development of society and increasing of population,environmental issues have become increasingly prominent,and the energy crisis need to be resolved Therefore,the development and use of clean energy is a common concern for researchers Supercapacitor is a new type of energy storage device.It has attracted widely attention due to its high power density,fast charge and discharge capability,long cycle life.However,traditional supercapacitors hinder the development of flexible supercapacitors due to their poor ductility,poor fatigue resistance and strong rigidity.Therefore,it is important to develop the flexible solid state supercapacitors with conductivity high capacitance and good flexibility.In this paper,a new strategy was adopted to simultaneously improve the toughness and electrochemical performance of microgel-reinforced conductive dual-network hydrogel electrodes.The conductive microgels were crosslinked to form the first network,which can dissipate energy to improve mechanical properties,stabilize the conductive network and improve the electrochemical performance.PEDOT and PPy conductive polymers can improve the electrical and electrochemical properties of hydrogel electrodes MR-PEDOT/PAAm/PPy DN Gel exhibited excellent mechanical properties(stress up to 1.1 MPa,strain up to 570%)and electrochemical properties(specific capacitance up to 220 F·g-1 at the current density of 0.5 A·g-1).At the same time,MR-PEDOT/PAAm/PPy DN Gel and MGSC showed excellent cycle stability.After cycling 1000 times,their capacitance retention rates reached 94%and 83%,respectively.The excellent performance exhibited of hydrogel electrode has a good application prospect in flexible devicesA polyacrylamide-dopamine-sodium sulfate hydrogel electrolyte with self-healing and strong adhesion function was prepared by free radical polymerization.The hydrogel has strong tensile properties and fracture toughness(stress up to 29.2 KPa,strain up to 2750%)After the self-healing process,the mechanical properties of the hydrogel can be restored to the original state.At the same time,MoS2@SnS2@C nanorods were successfully prepared by hydrothermal synthesis and high temperature calcination process.The obtained MoS2@SnS2@C nanorods electrode material and PAAm-PDA-Na2SO4 gel electrolyte were assembled to obtain a flexible stretchable symmetric supercapacitor(MoS2@SnS2@C-SC).The flexible MoS2@SnS2@C-SC shows excellent electrochemical performance and good electrochemical stability.The specific capacitance of the MoS2@SnS2@C-SC is 388 F·g-1 at the current density of 1 A·g-1.The energy density can reach 19.4 Wh·kg-1 at the power density of 300 W·kg-1.The MoS2@SnS2@C-SC has a capacitance retention of 99.1%after 5000 cycles at the current density of 5 A·g-1,which indicating the excellent electrochemical cycle stability of the flexible MoS2@SnS2@C-SC.Besides,We tested the electrochemical performance of the self-healing MoS2@SnS2@C-SC.By comparing the electrochemical properties of the hydrogel before and after self-healing,we found that the capacitance of the self-healing MoS2@SnS2@C-SC remained above 98%.It is proved that the MoS2@SnS2@C-SC after the fracture can be successfully repaired to the original state.At the same time,the MoS2@SnS2@C-SC can withstand large bending changes at different bending angles.After 1000 cycles of bending at a bending angle of 120°,the capacitance retention rate can still reach 91.7%.It indicates that the flexible device has great research value in flexible wearable devices.The ZnCo2O4 nanospheres with different internal structures were uniformly attached to the surface of carbon cloth(CC)by a low-cost hydrothermal method and temperature-controlled calcination method to form ZnCo2O4@CC electrode material.At a current density of 0.5 A·g-1,the electrode exhibits a specific capacitance of 882.5 F·g-1 and it still has a capacitance retention of 99.4%after cycling for 5000 cycles at the current density of 5.0 A·g-1.A highly viscous PAAm-PDA-Na2SO4 Gel was used as a gel electrolyte and the electrode material was assembled to a supercapacitor(ZCO-SC)and tested for electrochemical performance.Due to the strong adhesion of dopamine,ZnCo2O4@CC electrode material adheres well to PAAm-PDA-Na2SO4 gel electrolyte,which is useful to solve the problem of poor contact between electrode material and gel electrolyte in flexible supercapacitor.At the same time,due to the softness and ductility of PAAm,ZCO-SC can be bended and folded at any angles,and its capacitance performance is well maintained during the deformation process.ZCO-SC exhibited a specific capacitance of 252 F·g-1 at the current density of 0.5 A·g-1 and it still has a capacitance retention of 98.7%after cycling for 5000 cycles at the current density of 5.0 A·g-1.The superior electrochemical performance is attributed to the unique stability of the internal core-shell structure of the ZnCo2O4@CC electrode material and the strong adhesion of gel electrolyte.This experiment not only improves electrochemical performance for supercapacitor,but also provides a new option for flexible wearable devices.