Unlocking ultra-low temperature performance: an anti-freezing, high-conductivity, biodegradable hydrogel electrolyte...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Hydrogel electrolytes offer safety and flexibility for supercapacitors.
• Freezing at subzero temperatures severely degrades supercapacitor performance.
• Developing freeze-resistant electrolytes is crucial for extreme cold applications.

Purpose of the Study:

• To develop a freeze-resistant hydrogel electrolyte for supercapacitors operating at ultra-low temperatures.
• To investigate the structural and electrochemical properties of the novel electrolyte.
• To evaluate the performance and stability of supercapacitors using the developed electrolyte in extreme cold conditions.

Main Methods:

• Synthesized a freeze-resistant hydrogel electrolyte (SCG-Zn) using sodium hyaluronate, carboxymethyl chitosan, glycerol, and zinc chloride.
• Characterized the hydrogel's water binding network, ionic conductivity, and freezing point depression.
• Assembled supercapacitors and tested their electrochemical performance, cycling stability, and mechanical durability at various temperatures, including -60 °C.

Main Results:

• The SCG-Zn electrolyte exhibited a strongly bound water network, suppressing ice crystallization and enabling operation at -60 °C.
• Achieved high ionic conductivity (13.32 mS cm⁻¹ at -60 °C and 35.75 mS cm⁻¹ at 25 °C) due to zincophilic groups and Zn²⁺ pathways.
• Supercapacitors showed excellent cycling stability (97.6% capacity retention at 25 °C, 97.4% at -60 °C after 20,000 cycles) and mechanical flexibility.

Conclusions:

• The developed SCG-Zn hydrogel electrolyte effectively overcomes the freezing limitations of traditional hydrogels.
• This material enables reliable and high-performance supercapacitor operation in extreme cold environments.
• Presents a sustainable and effective solution for energy storage devices in harsh conditions.