Leveraging cation effect for low temperature aqueous Zn-based batteries.

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Anion-water interactions are known to lower freezing points in electrolytes.
• Cation-water interactions have been largely overlooked in antifreezing applications.
• Understanding cation effects is crucial for developing low-temperature aqueous devices.

Purpose of the Study:

• To investigate the impact of cation-water interactions on electrolyte freezing points.
• To explore the role of aluminum ions (Al³⁺) in modifying water structure and hydrogen bonding.
• To demonstrate the application of cation-engineered electrolytes in high-performance low-temperature batteries.

Main Methods:

• Investigated Al³⁺ cation effects on water structure and hydrogen bonding in aqueous electrolytes.
• Measured freezing point depression using Al³⁺-containing electrolytes.
• Fabricated and tested zinc-based symmetrical coin cells and zinc-polyaniline pouch cells at low temperatures.

Main Results:

• Al³⁺ weakens water hydrogen bonds, significantly lowering the freezing point to -117 °C at 2.8 m concentration.
• Dual-cation effects optimized ion diffusion and formed a protective Al-Zn alloy layer on the Zn electrode.
• Symmetrical Zn||Zn cells achieved 10,340 hours of stable Zn plating/stripping.
• Zn||polyaniline pouch cells showed 100% capacity retention after 500 cycles at -70 °C and delivered 115.5 mAh g^-1 at -80 °C.

Conclusions:

• Cation effects, specifically from Al³⁺, are a powerful strategy for tuning water structure in electrolytes.
• This approach enables the development of highly stable and efficient aqueous electrolytes for low-temperature energy storage devices.
• The findings open new avenues for designing advanced electrolytes for extreme condition applications.