Preparation And Properties Of Pseudocapacitors Based On Polymer Gel Electrolytes

Supercapacitor is an important energy storage device,which is widely used in the automotive industry,military production,communication equipment and other fields because of its significant advantages such as high power-density,long service life,safety and reliability,almost no maintenance and fast charging and discharging capabilities,and excellent cycle performance.From the working principle,supercapacitors can be divided into electric double layer supercapacitors,fake capacitance supercapacitors and hybrid supercapacitors.Due to the introduction of redox reaction,the pseudo-capacitive supercapacitor has obtained a specific capacitance and energy density much higher than that of the traditional electric double-layer supercapacitor,and the power storage capacity has been greatly improved.Solid-state electrolytes are gradually becoming the best choice for assembling devices because of their easy processing and easy packaging,high voltage window and high stability.Among them,the polymer gel electrolyte,as a solid electrolyte with excellent performance,also has good mechanical properties and electrical conductivity.Applying it to a pseudo-capacitive supercapacitor ensures that the device has good flexibility and long-term cycling performance while obtaining a high specific capacitance and energy density.This makes the prepared supercapacitors have a high use value and have broad application prospects in the field of wearable energy storage devices.In this paper,we prepared a polymer ionic gel electrolyte(PAAM-PVA-Li₂SO₄-BMIMBr)with polyacrylamide and polyvinyl alcohol as the matrix,N,N-methylene bisacrylamide(MBA)as crosslinker,and lithium sulfate and 1-butyl-3-imidazole bromide as conductive media.At room temperature,its conductivity can reach 39.3 m S cm^-1 and tensile strength can reach 269 k Pa.Assembling it with an activated carbon electrode by an all-in-one molding method,we have prepared a pseudo-capacitive supercapacitor with good deformability,high voltage window and high cycle performance.Its area capacitance can reach up to 284.8 m F cm^-2,mass capacitance of72.2 F g^-1,energy density of 25.3 Wh kg^-1.After 5000 cycles at a current density of 10m A cm^-2,the Coulomb efficiency remains at 96%and the capacitance retention rate is99.7%.According to the low specific capacitance of the activated carbon electrode,we prepared a series of active substances(P-MX)with multilayer titanium carbide(MXene)as the matrix aniline as the monomer polymerization in situ(P-MX),of which the flexible electrode area capacitance prepared with P-M10 can reach 1435.8m F cm^-2,the mass capacitance is 1196.5 F g^-1,and the energy density is 105.8 Wh kg^-1.After that,we designed a gel electrolyte with MXene as the crosslinker,polyacrylic acid as the polymer matrix,and sulfuric acid as the conductive medium,which has a conductivity of up to 165 m S cm^-1,elongation at break of 242%,and tensile strength of176 k Pa.The pseudo-capacitive supercapacitor P-M10-MG,which is assembled with the P-M10 electrode,has a specific capacitance of 222 F g^-1 and an energy density of19.7 Wh kg^-1.After 10,000 cycles at a current density of 20 m A cm^-2,the capacitance retention rate can reach 98.5%.The prepared devices have good variability and high use value.