LAUSR

Abstract The broad temperature adaptability of vanadium redox flow battery (VFB) has been studied in our two previous works, including the study on the broad temperature adaptability of the vanadium electrolytes (Electrochim. Acta, 2016, 187, 525) and battery performance (Electrochim. Acta, 2016, 191, 695) with a fixed electrolyte composition of 1.5 M vanadium in 3.875 M total sulfate. As a follow-up study, the stability of the vanadium electrolytes with different valences, total vanadium concentrations and sulfuric acid concentrations is studied at a broad temperature range. In this work, the static stability of the vanadium electrolytes with four valences (V2+, V3+, VO2+ and VO2+), different total vanadium concentrations (0.4–2.2 M) and various sulfuric acid concentrations (1.5–3.0 M) is researched over a wide temperature range (−35 to 60 °C). Subsequently, the cell performance of VFBs with selected electrolyte compositions was evaluated at different temperatures and different current densities. This work systematically investigates the effects of the total vanadium concentration and sulfuric acid concentration on the temperature adaptability of VFBs for the first time as we know, which is an important reference for the battery's application.