Preparation And Electrochemical Properties Research Of The PVA Polymer Electrolyte Membrane Which Used In Solid-State Supercapacitor

All solid-state super capacitor?SSCs?,which are composed by polymer gel electrolyte,have a thinner,lighter,cheaper and flexible characteristics,and can be used as energy device of the wearable and portable electronic equipment.It has a very broad application prospects.In this paper,the PVA-H₃PO₄ gel electrolyte was prepared by chemical crosslinking.The effect of its composition and water content on the conductivity of the electrolyte were studied further.Using electrodeposition method,polyaniline-carbon paper electrode were prepared and assembled the SSCs with PVA-H₃PO₄ gel electrolyte.The phase structure and thermal stability of PVA-H₃PO₄ gel electrolyte and polyaniline-carbon paper electrode were studied by X-ray diffraction?XRD?,fourier transform infrared spectroscopy?FT-IR?,thermogravimetric analysis?TGA?,scanning electron microscopy?SEM?;and the electrochemical properties were tested by cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?,electrochemical impedance spectroscopy?EIS?.The specific research contents and results are as follows:?1?Crosslinked polyvinyl alcohol?PVA?with glutaraldehyde?GA?,use phosphoric acid as proton source and the initiation agent preparation of the PVA-H₃PO₄ polymer electrolyte.The effect of phosphate acid content on the conductivity of the polymer gel electrolyte were studied.The experimental results showed that with the increase of H₃PO₄ content,the proton conductivity of the electrolyte membrane increases first and then decreases.At room temperature,when the mass ratio of PVA to H₃PO₄ is 1:6,the proton conductivity can reach 0.093 s·cm-1,and it has good electrochemical stability.?2?The water content within the PVA-H₃PO₄ gel electrolyte were monitored by differential analysis method and controlled as 30%,50% and 70%?mass percent?of the electrolyte membrane.It was found that the polymer gel electrolyte membrane with 50% water content,which has a minimum activation energy of 6.58kJ·mol-1,the shortest relaxation time of 6.8ms,and it also has good electrochemical stability.?3?Electrodeposition of polyaniline on the carbon paper were realized by cyclic voltammetry,and it was used as polyaniline-carbon paper electrode to assemble the SSCs whose electrolyte is PVA-H₃PO₄ gel electrolyte which has 50% water content.It was shown that the surface of polyaniline-carbon paper electrode is porous foam structure,which greatly increased the contact area between the electrolyte and the electrode,and reduced the contact resistance between them.Therefore,the specific capacity of the SSCs were improved.With the charge and discharge current density of 10mA·cm-2,the specific capacitance of the whole solid state supercapacitor can be up to 1.75F·cm-2.After 1000 charge discharge cycles,its specific capacity was 1.29Fcm-2.Its capacity retention rate is 89.0% compared to the first charge discharge capacity.