Prospective Life Cycle Assessment of Chemical Electrolyte Recycling for Vanadium Flow Batteries: A Comprehensive Study

Abstract

Battery storage systems are an important key element for a successful energy transition. Increasingly, the focus is also on the sustainability analysis of the various energy storage technologies. In particular, the vanadium flow battery (VFB) is mentioned as a promising day storage technology. Nevertheless, its high cost and environmental impacts are attributed to its electrolyte. It is assumed that this issue can be addressed through reprocessing and reuse. The aim of this study is to provide, for the first time in the literature, information on the process design and the potential emissions of the treatment of end-of-life (EoL) vanadium electrolyte with various critical impurities, in order to be able to validly estimate the total emissions of VFB with recycled electrolyte. Four different scenarios are considered, combining treatment steps for electrolyte with different critical contaminations, revealing detailed mass and energy balances. The life cycle assessment provides valuable results for the sustainability assessment of the EoL vanadium electrolyte and the entire VFB system. The treatment of the electrolyte leads to significantly lower CO2 emissions (−79.2% to −99.8%) compared to the primary electrolyte and must be taken into account in future when assessing the sustainability of the VFB.