A Stable Aqueous Zinc-Thiocyanogen Battery at -30 °C

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-ion batteries offer safety and eco-friendliness but suffer from poor low-temperature performance due to electrolyte freezing.
• Electrolyte solidification below the freezing point causes rapid capacity degradation in conventional aqueous systems.

Purpose of the Study:

• To develop a stable aqueous zinc-ion battery capable of operating effectively at sub-zero temperatures.
• To investigate a water-in-salt electrolyte formulation that mitigates freezing issues for enhanced low-temperature energy storage.

Main Methods:

• Fabrication of a Zn-(SCN)2 battery system incorporating a novel water-in-salt electrolyte with a -89°C freezing point.
• Electrochemical cycling and performance evaluation of the battery at -30°C and 0°C.

Main Results:

• The developed Zn-(SCN)2 battery demonstrated remarkable stability, with 2300 cycles at -30°C and 99.7% capacity retention.
• At 0°C, the battery achieved a high areal specific capacity of 984.2 μAh cm⁻² and an energy density of 1.18 mWh cm⁻².

Conclusions:

• The water-in-salt electrolyte effectively suppresses water freezing, enabling robust low-temperature operation of aqueous zinc-ion batteries.
• This research presents a promising pathway for developing high-performance, safe, and environmentally friendly energy storage solutions for cold environments.