Lean-Water Gel Electrolyte Enables Zinc Ion Battery at -70 °C

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc ion batteries offer safe, affordable energy storage but suffer from water-related issues like parasitic reactions and poor low-temperature performance.
• Water's freezing point limits zinc ion transport and battery operation below -40°C, hindering practical applications.

Purpose of the Study:

• To design a water-in-polymer electrolyte that confines water, mitigating drawbacks of aqueous electrolytes.
• To enhance the electrochemical stability and low-temperature performance of zinc ion batteries.

Main Methods:

• A weak-solvation monomer-directed polymerization technique initiated by protons was used to create the water-in-polymer electrolyte.
• Proton-initiated polymerization confined water molecules within a polymer matrix.
• Electrochemical performance was evaluated using symmetric zinc cells and Zn||Zn0.58V2O5 full cells.

Main Results:

• The water-in-polymer electrolyte significantly suppressed water-induced parasitic reactions and widened the electrochemical window to 2.59 V.
• High ionic conductivity (0.36 mS cm⁻¹) was achieved at -70°C due to fast ion transport and favorable interfacial desolvation.
• Symmetric Zn cells demonstrated excellent cycle stability over 10,000 hours at room temperature and 700 hours at -40°C.

Conclusions:

• The developed electrolyte strategy effectively confines water, overcoming limitations of traditional aqueous electrolytes.
• This approach enables stable and efficient operation of zinc ion batteries at sub-zero temperatures, paving the way for advanced energy storage solutions.
• The findings inspire further research into water confinement for improved aqueous battery performance.