, Volume 21, Issue 1, pp 167-174
Date: 09 May 2014

Effects of pyridine carboxylic acid on the positive electrolyte for vanadium redox flow battery

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Abstract

In this work, dipicolinic acid and quinolinic acid are employed as additives to improve the thermal stability and electrochemical performance for the positive electrolyte of vanadium redox flow battery (VRFB). Both additives can restrain the precipitation of V2O5 from V(V) electrolyte. The concentration of remained V(V) ions in electrolyte with 1 mol% quinolinic acid is 1.58 M at 40 °C after 90 h, 0.41 M higher than that of the pristine electrolyte. CV and LSV measurements show that the electrolyte with quinolinic acid exhibits superior electrochemical activity and reaction kinetics with larger exchange current density and reaction rate constant, compared with the pristine electrolyte. A high coulombic efficiency of over 95 % and energy efficiency of 74.88 % are obtained. The XPS spectra show that quinolinic acid can absorb on the surface of graphite felts, providing more activity sites for the V(IV)/V(V) redox reaction.