Defining Metal-Impurity Thresholds for Hydrogen Evolution in Sealed Vanadium Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Vanadium ion batteries (VIBs) offer a safe, scalable aqueous energy storage solution.
• Sealed VIBs require suppression of the hydrogen evolution reaction (HER) for stability.
• Metal ion impurities can influence HER in VIBs.

Purpose of the Study:

• To systematically investigate the impact of metal ion impurities on HER in sealed VIBs.
• To identify impurity-specific thresholds for HER onset.
• To provide guidance for vanadium liquid electrode purity specifications.

Main Methods:

• Introduced representative metal ion impurities into vanadium liquid electrodes.
• Monitored internal pressure changes during cycling as an indicator of gas evolution.
• Analyzed impurity behavior, including solubility effects.

Main Results:

• Identified distinct categories of impurity behavior affecting HER.
• Noble metals strongly promoted HER, while some species showed inertness due to low solubility.
• Established impurity-specific threshold concentrations for irreversible pressure build-up.

Conclusions:

• Impurity control is critical for managing HER in sealed VIBs.
• Thresholds provide practical guidance for electrode purity standards.
• This research bridges fundamental science with industrial needs for stable VIB operation.