Hydrogel electrolytes have received increasing research attention due to their high ionic conductivity and ability to overcome the leakage problems in conventional liquid electrolytes. In this study, a free radical polymerization method was used to prepare polyacrylamide hydrogels, with kaolinite employed as a physical crosslinker, and subsequently soaked in 1 M potassium hydroxide (KOH), 1 M sulfuric acid (H₂SO₄), and 1 M potassium chloride (KCl) for 24 h to provide ions and introduce ionic conductivity. The ionic conductivity of the hydrogel electrolytes was systematically evaluated using electrochemical impedance spectroscopy (EIS) at room temperature (27 °C) and a across a temperature range of 30 to 100 °C. Among the tested hydrogels, the H2SO4-soaked hydrogel (AAM/H2SO4) demonstrated the highest ionic conductivity of 6.77 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11581_2025_6325_Article_IEq1.gif" Format="GIF" Height="18" Rendition="HTML" Resolution="72" Type="Linedraw" Width="47" /> </InlineMediaObject> <EquationSource Format="TEX">$\times {10}^{-2}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>2</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> S/cm and the lowest activation energy of 0.0312 eV, attributed to the complete ionization of H2SO4 and its diprotic nature. The electrochemical performance of the fabricated hydrogels was further assessed in an electric double-layer capacitor (EDLC) using activated carbon electrodes. Characterization techniques such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses were performed. By having the lowest resistance and highest conductivity, the AAM/H2SO4 EDLC demonstrated a maximum specific capacitance of 71.00 F/g at a scan rate of 5 mVs−1 and 61.30 F/g at a current density of 300 mAg−1. These findings highlight the potential of AAM/H2SO4 hydrogels as high-performance electrolytes for energy storage applications, offering a promising solution to the limitations of traditional liquid electrolytes.

Studies of ionic conduction properties of polyacrylamide hydrogel polymer electrolytes at different medium (alkaline, acid, and salt) via impedance approach

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发表日期：

2025年4月23日

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Fakhruddin A.,
Fathiah Kamarulazam,
N. K. Farhana,
M. Pershaanaa,
Shahid Bashir,
S. Ramesh,
K. Ramesh

摘要

Hydrogel electrolytes have received increasing research attention due to their high ionic conductivity and ability to overcome the leakage problems in conventional liquid electrolytes. In this study, a free radical polymerization method was used to prepare polyacrylamide hydrogels, with kaolinite employed as a physical crosslinker, and subsequently soaked in 1 M potassium hydroxide (KOH), 1 M sulfuric acid (H₂SO₄), and 1 M potassium chloride (KCl) for 24 h to provide ions and introduce ionic conductivity. The ionic conductivity of the hydrogel electrolytes was systematically evaluated using electrochemical impedance spectroscopy (EIS) at room temperature (27 °C) and a across a temperature range of 30 to 100 °C. Among the tested hydrogels, the H₂SO₄-soaked hydrogel (AAM/H₂SO₄) demonstrated the highest ionic conductivity of 6.77 $\times {10}^{-2}$ $\times 10^{- 2}$ S/cm and the lowest activation energy of 0.0312 eV, attributed to the complete ionization of H₂SO₄ and its diprotic nature. The electrochemical performance of the fabricated hydrogels was further assessed in an electric double-layer capacitor (EDLC) using activated carbon electrodes. Characterization techniques such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) analyses were performed. By having the lowest resistance and highest conductivity, the AAM/H₂SO₄ EDLC demonstrated a maximum specific capacitance of 71.00 F/g at a scan rate of 5 mVs⁻¹ and 61.30 F/g at a current density of 300 mAg⁻¹. These findings highlight the potential of AAM/H₂SO₄ hydrogels as high-performance electrolytes for energy storage applications, offering a promising solution to the limitations of traditional liquid electrolytes.