The Performance Of Redox Gel Polymer Electrolyte In Supercapacitor

The performance of the gel polymer electrolyte is closely related to the performance of the capacitor.However,the normal gel polymer electrolyte had low ion conductivity and small capacitance contribution.In order to solve these problems,this paper combines the characteristics of electrochemical double capacitance and pseudocapacitance to increase the performance of gel electrolyte and specific capacity of supercapacitors.?1?Graphene oxide?GO?modified polyvinyl alcohol-sodium sulfate-sodium molybdate?GO/PVA-Na₂SO₄-Na₂MoO₄,GPSS?neutral gel polymer electrolyte was preparaed.Concerning GPSS//CP and GPSS//NiMoO₄/CP supercapacitors with carbon paper?CP?electrodes and nickel molybdate/carbon paper?NiMoO₄/CP?electrodes,the oxidation-reduction reaction of MoO₄^2-carried out at the electrode interface and and Ni²⁺carried out at the electrode itself realize the improvement of the pesudocapacitance performance of GPSS//NiMoO₄/CP supercapacitor in the neutral electrolyte.?2?Polyvinyl alcohol-phosphoric acid-molybdate-phosphoric acid(PVA-H₃PO₄-Na₂MoO₄-PMo₁₂,PPSP)acidic gel polymer electrolyte was preparaed.After combinng PPSP//CP and PPSP//PMo₁₂/PANI/CP supercapacitors with CP electrode and phosphomolybdic acid/polyaniline/carbon paper(PMo₁₂/PANI/CP)electrode,the synergistic effect between Na₂MoO₄ and PMo₁₂ and the redox reaction of the electrode itself are simultaneously used to increase the specific capacitance of supercapacitors;?3?Polyvinyl alcohol-hydrogen Potassium oxide-potassium iodide?PVA-KOH-KI?alkaline gel polymer electrolyte was preparaed.Concerning PVA-KOH-KI//CP and PVA-KOH-KI//NiMoO₄/CP supercapacitor with CP electrode and NiMoO₄/CP electrode,the oxidation-reduction reaction of I^-carried out at the electrode interface and Ni²⁺carried out at the electrode itself can improve the specific capacity and cycle stability of supercapacitors.The specific research work of this paper includes the following three aspects.?1?Preparation and Application of GO/PVA-Na₂SO₄-Na₂MoO₄ Neutral Redox Gel Polymer ElectrolyteGO/PVA-Na₂SO₄-Na₂MoO₄?GPSS?neutral redox gel polymer electrolyte was preparaed by sol-gel method.Due to the“super-high”way for electrolyte ions transportation provided by GO,the ionic conductivity increased from 4.33 mS cm^-1 for PVA-Na₂SO₄-Na₂MoO₄?PSS?to28.86 mS cm^-1 for GPSS with optimal GO/PVA mass ratio of 0.6%.The specific capacitance of CP supercapacitors was improved from 15.91 mF cm^-2 for GO/PVA-Na₂SO₄?GPS?//CP to41.67 mF cm^-2 for GPSS//CP at 0.5 mA cm^-2.In addition,because the redox reaction is introduced to the electrode interface and itself simultaneously,the specific capacitance and energy density of GPSS//NiMoO4/CP supercapacitor can reach to 78.18 mF cm^-2 and 131.39mWh m^-2 at 0.5 mA cm^-2 and an output voltage of 1.1 V.What's more,the cycling capacitance retention can reach 85%after 1000 cycles at 0.5 mA cm^-2.The GPSS//NiMoO₄/CP supercapacitor exhibits good electrochemical performance in neutral electrolytes.?2?Preparation and Application of PVA-H₃PO₄-Na₂MoO₄-PMo₁₂ Acdic Redox Gel Polymer ElectrolytePVA-H₃PO₄-Na₂MoO₄-PMo₁₂?PPSP?acid redox gel polymer electrolyte was prepared by sol-gel method.The ionic conductivity increased from 12.75 mS cm^-1 for PVA-H3PO4-Na2MoO4 and 17.23 mS cm^-1 for PVA-H3PO4-PMo12 to 25.64 mS cm^-1 for PPSP when the optimal ratio of PMo₁₂:Na₂MoO₄ is 2:1.Due to the synergistic effect between Na₂MoO₄ and PMo₁₂,the specific capacitance and energy density of PPSP//CP supercapacitors can reach to129.2 mF cm^-2 and 179.3 mWh m^-2 at a current density of 0.5 mA cm^-2,which is higher than that of PPS//CP and PPP//CP supercapacitors(48.05 mF cm^-2,66.7 mWh m^-22 and 45.3 mF cm^-2,62.9 mWh m^-2).The PPSP//PMo₁₂/PANI/CP supercapacitor was assembled and it has a specific capacitance and energy density of 287.5 mF cm^-2 and 399.3 mWh m^-22 at 0.5 mA cm^-2.PPSP//PMo₁₂/PANI/CP supercapacitors achieve a significant increase in specific capacitance.?3?Preparation and Application of PVA-KOH-KI Alkaline Redox Gel Polymer ElectrolytePVA-KOH-KI alkaline redox gel polymer electrolyte was prepared by sol-gel method.The ionic conductivity increased from 12.92 mS cm^-1 for PVA-KOH to 29.24 mS cm^-1 for PVA-KOH-KI with optimal KI:PVA mass ratio of 0.4:1.The specific capacity and energy density of PVA-KOH-KI//CP supercapacitors can reach to 129.1 mF cm^-2 and 179.4 mWh m^-2 at 0.5mA cm^-2,which is much higher than that of PVA-KOH//CP supercapacitor(39.6 mF cm^-2,55.0mWh m^-2).The improved capacitance performance can be attributed to the pseudocapacitance through reversible redox reaction of I^-.the specific capacity retention of the PVA-KOH-KI//CP supercapacitor was 82%after 1000 cycles at 0.5 mA cm^-2.the specific capacitance and energy density of PVA-KOH-KI//NiMoO₄/CP supercapacitor is 187.9 mF cm^-2 and 260.9 mWh m^-22 at a current density of 0.5 mA cm^-2.The specific capacity retention of it was 84%after 1000 cycles at 0.5 mA cm^-2.The PVA-KOH-KI//NiMoO₄/CP supercapacitor also achieves improved cycle stability while ensuring a higher specific capacity.