Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Gel-like electrolytes are crucial for advanced batteries and supercapacitors, but face a trade-off between ion conductivity and mechanical strength.
• Developing flexible and robust electrolytes with high performance remains a significant challenge in energy storage technology.

Purpose of the Study:

• To investigate the integration of ionic hyperbranched polymers into cellulose-based ionogels to overcome the conductivity-mechanical property trade-off.
• To enhance both ionic conduction and mechanical robustness in gel electrolytes for improved energy storage devices.

Main Methods:

• Synthesized ionogels using coassembled cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) as a porous framework.
• Incorporated ionic hyperbranched polymers with varying ionic group densities into the cellulose framework for ionic liquid immersion.
• Characterized the structural, mechanical, and electrochemical properties of the resulting ionogels and supercapacitors.

Main Results:

• The addition of hyperbranched polymers created lightweight, porous, and shape-persistent ionogels with enhanced hydrogen bonding interactions.
• Achieved a 2-fold increase in ionic conductivity and a significant enhancement in Young's modulus, tensile strength, and toughness.
• Developed thin-film gel supercapacitors exhibiting 85% capacitance retention after 10,000 bending cycles, demonstrating excellent electrochemical stability.

Conclusions:

• Ionic hyperbranched polymers effectively improve both ionic conductivity and mechanical properties of cellulose-based ionogels.
• These novel ionogels offer a promising pathway for developing high-performance, flexible, and durable electrolytes for next-generation energy storage devices.
• The study provides new insights into designing advanced gel electrolytes with sustained performance under mechanical stress.