Preparation Of Ti₃C₂T_x Base Electrode And Electrolyte And Its Application In Flexible Supercapacitors

Flexible supercapacitors（FSCs）have become an important clean and sustainable energy storage device because of their electrochemical advantages such as fast charging and discharging,long cycle life,high energy density and so on.Electrolytes and electrodes are important components that determine the electrochemical performance of supercapacitors.Polymer hydrogels are the preferred electrolyte materials because of their high biosafety,flexibility and abundant porous structure,but their application is limited by high internal resistance.Ti₃C₂T_x based electrode material has been paid much attention because of its high conductivity and large specific surface area.How to limit its self-stacking is the primary problem at present.Ti₃C₂T_x was introduced into polyacrylamide/calcium alginate（PC）hydrogel electrolyte to reduce internal resistance（IR）and improve interface adhesion.Polyacrylamide/calcium alginate@Ti₃C₂T_x（PCT）composite hydrogel was prepared by in-situ polymerization.Their microstructure,preparation mechanism,mechanical properties and adhesion properties to various substrates were studied respectively.The flexible supercapacitor was assembled by using composite hydrogel as electrolyte and two self-made Ti₃C₂T_x films as electrodes.It was found that the composite hydrogels adhered to various substrates and reduced the voltage drop of FSCs from 163 m V to78.9 m V.When the current density is 1.07 m A cm^-2,the specific capacitance of the FSCs is 1051.9 m F cm^-2.When the current density is 18.7 m A cm^-2,the capacitance retention rate is as high as 96%and the energy density is as high as 32.3 Wh kg^-1.At the same time,it can sensitively monitor human movements,such as finger bending,frowning,swallowing,etc.Porous carbon（PC）and carbon nanotubes（CNTs）were inserted into the Ti₃C₂T_xnanosheets by vacuum filtration method to prepare TC_xP_y films of different proportions.The morphology and phase composition of the samples were characterized by SEM,XRD and FTIR.The effects of different proportions of Ti₃C₂T_x nanosheets,carbon nanotubes and porous carbon on the mechanical and electrochemical properties of TC_xP_y films were studied by electrochemical and mechanical tests.The results show that the Ti₃C₂T_x/CNT/PC（TCP）thin films were able to show an ultra-high area ratio capacitance of 1346.3 m F cm^-2 at 3 m A cm^-2,which remained above 70%when the current density was increased to 20 m A cm^-2.Its equivalent circuit resistance is only0.52Ω.It has large surface energy density of 119.7μWh cm^-2 at 1200μW cm^-2,and excellent magnification capacity of more than 70%when the power density is increased by about 7 times.