Dual-Salt Chaotropic Eutectic Electrolyte for Enhancing Low-Temperature Zinc-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (ZIBs) suffer performance loss at low temperatures due to water freezing.
• The Hofmeister effect offers a potential mechanism to disrupt water's hydrogen-bonding network.

Purpose of the Study:

• To develop a novel electrolyte for ZIBs that overcomes low-temperature performance degradation.
• To investigate the impact of a dual-salt super-chaotropic eutectic electrolyte on ZIB freezing point and electrochemical stability.

Main Methods:

• Formulation of a eutectic electrolyte using Zn(ClO4)2·6H2O, NaClO4·H2O, and acetamide.
• Characterization of the electrolyte's freezing point and electrochemical properties.
• Testing of Zn||sodium vanadium phosphate (NVP) batteries at low temperatures.

Main Results:

• Achieved an ultra-low electrolyte freezing point of -75.9 °C.
• Demonstrated stable cycling of Zn||NVP batteries at -20 °C for over 5500 cycles with 81.2% capacity retention.
• Observed minimal capacity fade (94.8% retention after 250 cycles) in pouch cells at -20 °C.

Conclusions:

• The developed chaotropic eutectic electrolyte effectively suppresses water freezing and enhances low-temperature ZIB performance.
• This electrolyte design offers a promising strategy for developing robust, long-lasting ZIBs for cold environments.