Establishing High-Performance Quasi-Solid Zn/I₂ Batteries with Alginate-Based Hydrogel Electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Zinc-iodine (Zn/I2) batteries are promising for large-scale energy storage due to high-capacity reactions.
• Key limitations include triiodide ion (I3-) shuttling and side reactions on zinc anodes, hindering battery lifespan.

Purpose of the Study:

• To design and synthesize an alginate-based polyanionic hydrogel electrolyte.
• To address the limitations of Zn/I2 batteries by preventing I3- shuttling and improving Zn anode stability.

Main Methods:

• Synthesized an alginate-based polyanionic hydrogel electrolyte using ion exchange and Zn2+-induced cross-linking.
• Investigated the hydrogel's ability to block I3- shuttling and facilitate cation transport.
• Evaluated the hydrogel's effect on Zn anode cycling durability and interfacial properties.

Main Results:

• The hydrogel electrolyte effectively blocked I3- shuttling and stabilized Zn plating/stripping for over 600 hours.
• Zn/I2 full batteries with the hydrogel electrolyte achieved a high capacity of 183.4 mAh g-1 with 97.6% retention after 200 cycles.
• Demonstrated a 77.4% higher residual capacity compared to traditional ZnSO4 aqueous electrolytes.

Conclusions:

• Alginate-based polyanionic hydrogel electrolytes show significant potential for improving the performance and lifespan of aqueous Zn/I2 batteries.
• The designed hydrogel effectively mitigates key issues like ion shuttling and zinc anode degradation.
• This work highlights the importance of electrolyte design in advancing next-generation energy storage systems.