Publications Details

Quantification of Chlorine Gas Generation in Mixed-Acid Vanadium Redox Flow Batteries

Wittman, Reed M.; Laros, James H.; Laros, James H.; Anderson, Travis M.; Preger, Yuliya P.

Mixed-acid vanadium redox flow batteries (VRFBs) are an attractive option to increase energy density and temperature stability relative to conventional VRFBs for grid energy storage applications. However, the inclusion of hydrochloric acid introduces a significant safety risk through chlorine gas (Cl2) evolution. Here, we present the first direct measurements of Cl2 generation in a mixed-acid VRFB. Cl2 is generated through an electrochemical reaction when the system is charged above ∼74% state of charge with concentrations exceeding 3% of the system headspace. We explore how Cl2 evolution is enabled and propose mitigation strategies.