Non-Drying Hydrogel Polyelectrolytes via Polymer-Assisted Cation Solvation-Confinement Toward H₂O for...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Conventional hydrogel electrolytes for aqueous micro-supercapacitors (MSCs) suffer from poor water retention and limited electrochemical windows.
• These limitations result in low operational voltage and energy density in pure aqueous MSCs.
• Inadequate control over water molecules in hydrogels is a key challenge.

Purpose of the Study:

• To enhance water retention and electrochemical window of polyelectrolytes for aqueous MSCs.
• To develop a polymer-assisted cation solvation-confinement strategy.
• To improve the performance and safety of micro-power sources.

Main Methods:

• Developed poly(acrylamide-hydroxypropyl acrylate) (PAM-HPA) polyelectrolytes using a polymer-assisted cation solvation-confinement strategy.
• Investigated water retention properties through long-term air exposure tests.
• Fabricated and tested activated carbon-based and MXene-based aqueous symmetric MSCs with the developed polyelectrolytes.

Main Results:

• PAM-HPA polyelectrolytes demonstrated no water evaporation after 3.5 months of air exposure at room temperature.
• Activated carbon-based MSCs achieved a record 2.5 V voltage and 187.9 µWh cm⁻² areal energy density.
• MSCs with MXene microelectrodes maintained a high voltage (>2 V) and ultra-long cycle life, retaining 90% capacitance after 60 °C heat treatment.

Conclusions:

• The polymer-assisted cation solvation-confinement strategy effectively enhances water retention and electrochemical window of polyelectrolytes.
• This approach leads to high-performance, safe, and stable aqueous MSCs with significantly improved energy density and operational voltage.
• The developed non-drying polyelectrolytes offer a promising pathway for advanced micro-power sources.