Polyacrylamide-based hydrogel electrolyte for modulating water activity in aqueous hybrid batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Zinc-ion and hybrid aqueous batteries offer low-cost alternatives to lithium-ion batteries.
• Commercialization is hindered by side reactions, limited stability, and electrolyte leakage.
• Hydrogel electrolytes present a promising solution due to their stability, low cost, and minimal leakage.

Purpose of the Study:

• To develop a dual-function hydrogel electrolyte for enhanced aqueous battery performance.
• To improve electrochemical stability and reduce side reactions in zinc-based battery systems.
• To explore the potential of polyacrylamide-based hydrogels as integrated electrolyte-separators.

Main Methods:

• Synthesis of a dual-function hydrogel electrolyte using polyacrylamide and poly(ethylene dioxythiophene):polystyrene (PPP).
• Swelling the hydrogel in a binary ethylene glycol and water solution (EG 10%) for enhanced stability.
• Characterization of ionic conductivity, electrochemical stability (linear sweep voltammetry), and specific capacity.

Main Results:

• The PPP hydrogel electrolyte demonstrated good ionic conductivity (1.6 × 10^-3 S cm^-1) and electrochemical stability (> 2.5 V).
• The PPP-based system achieved a specific capacity of 119.2 mA g^-1, outperforming the aqueous electrolyte (80.4 mA g^-1).
• Rechargeable hybrid aqueous batteries with the PPP hydrogel achieved over 600 cycles with 99% Coulombic efficiency.

Conclusions:

• The developed dual-function hydrogel electrolyte effectively enhances the stability and performance of zinc-based aqueous batteries.
• Polyacrylamide-based hydrogels show significant potential as integrated electrolyte-separators, paving the way for safer and more durable energy storage solutions.
• This work inspires further research into advanced hydrogel electrolytes for next-generation aqueous battery systems.