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The Influence of Free Acid in Vanadium Redox‐Flow Battery Electrolyte on “Power Drop” Effect and Thermally Induced Degradation
Author(s) -
Roznyatovskaya Nataliya V.,
Fühl Matthias,
Roznyatovsky Vitaly A.,
Noack Jens,
Fischer Peter,
Pinkwart Karsten,
Tübke Jens
Publication year - 2020
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.202000445
Subject(s) - vanadium , flow battery , electrolyte , chemistry , inorganic chemistry , drop (telecommunication) , sulfate , redox , sulfuric acid , analytical chemistry (journal) , electrode , chromatography , organic chemistry , telecommunications , computer science
A series of vanadium redox‐flow battery (VRFB) electrolytes at 1.55 m vanadium and 4.5 m total sulfate concentration are prepared from vanadyl sulfate solution and tested under conditions of appearance of “power drop” effect (discharge at high current density from high state‐of‐charge). A correlation between the initial electrolyte composition, the thermal stability of catholyte, and the susceptibility of VRFB to exhibit a “power drop” effect is derived. The increase in total acidity to 3 m , expressed as concentration of sulfuric acid in precursor vanadyl sulfate solution, enables “power drop”‐free operation of VRFB at least at 75 mA cm −2 . Thermally‐induced degradation of electrolyte is evaluated based on decrease in vanadium concentration in the electrolyte series after exposure to the temperature of 45 °C and based on characterization of catholytes series using 51 V, 17 O, and 1 H nuclear magnetic resonance spectroscopy.