Cold-Optimized Zinc-Ion Batteries: Enhanced Stability at -5 °C

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) are widely studied, but their performance mechanisms at intermediate temperatures are not well understood.
• Limited research exists on AZIBs operating between room temperature and ultralow temperatures, particularly in the -15°C to 25°C range.

Purpose of the Study:

• To investigate the electrochemical performance of AZIBs within the intermediate temperature range of 25°C to -15°C.
• To elucidate the mechanisms behind performance variations in AZIBs at sub-zero temperatures.
• To identify optimal operating conditions for enhanced AZIB stability and efficiency.

Main Methods:

• Electrochemical performance testing of an AZIB with a double hydroxide cathode using a 3 M ZnSO4 electrolyte.
• Systematic evaluation across temperatures from 25°C down to -15°C.
• Spectroscopic analysis and theoretical calculations to understand reaction mechanisms.

Main Results:

• Optimized battery performance and significantly enhanced cycling stability were observed at -5°C compared to 25°C.
• Unfavorable proton (H+)-associated reactions at the cathode and anode were suppressed at -5°C.
• Changes in the electrolyte at -5°C, including reduced water activity and altered hydrogen bonding, impeded proton diffusion via the Grotthuss mechanism.

Conclusions:

• Sub-zero temperatures, specifically -5°C, can enhance AZIB cycling stability by suppressing detrimental proton reactions.
• Modified electrolyte properties at intermediate sub-zero temperatures favor zinc-ion (Zn2+) charge storage over proton-related side reactions.
• This study offers insights for developing AZIBs that operate effectively in near-freezing environments.