Electrical and Capacitive Response of Hydrogel Solid-Like Electrolytes for Supercapacitors.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Flexible hydrogels are promising solid-like electrolytes for energy storage devices like supercapacitors.
• Their lightweight and anti-deformation properties are advantageous for applications such as wearable electronics.

Purpose of the Study:

• To comparatively study four ionic conductive hydrogels derived from biopolymers (κ-carrageenan, carboxymethyl cellulose, poly-γ-glutamic acid, and polyesteramide) doped with NaCl.
• To evaluate their suitability as semi-solid electrolytes for supercapacitors based on electrical and capacitive behaviors.

Main Methods:

• Synthesis and characterization of four distinct biopolymer-derived hydrogels.
• Assessment of hydrogel morphology and swelling ratio.
• Electrochemical impedance spectroscopy to measure bulk conductivity and capacitive behavior.
• Fabrication of supercapacitor devices with poly(3,4-ethylenedioxythiophene) electrodes.

Main Results:

• Hydrogel swelling ratios ranged from 483% to 2356%.
• Bulk conductivity values were 76, 48, 36, and 34 mS/cm for polyesteramide, poly-γ-glutamic acid, κ-carrageenan, and carboxymethyl cellulose hydrogels, respectively.
• The polyesteramide hydrogel exhibited the highest conductivity and capacitance, attributed to its homogeneous micro- and nanoporous structure.

Conclusions:

• The polyesteramide hydrogel demonstrates optimal properties for use as a semi-solid electrolyte in supercapacitors.
• Its porous morphology enhances ion transport and electrode interfacial contact, leading to improved device performance.
• This study highlights the importance of hydrogel porous structure in designing next-generation flexible energy storage devices.