%0 Journal Article
%T Vanadium Electrolyte for All-Vanadium Redox-Flow Batteries: The Effect of the Counter Ion
%J Batteries | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/batteries5010013
%X In this study, 1.6 M vanadium electrolytes in the oxidation forms V(III) and V(V) were prepared from V(IV) in sulfuric (4.7 M total sulphate), V(IV) in hydrochloric (6.1 M total chloride) acids, as well as from 1:1 mol mixture of V(III) and V(IV) (denoted as V 3.5+) in hydrochloric (7.6 M total chloride) acid. These electrolyte solutions were investigated in terms of performance in vanadium redox flow battery (VRFB). The half-wave potentials of the V(III)/V(II) and V(V)/V(IV) couples, determined by cyclic voltammetry, and the electronic spectra of V(III) and V(IV) electrolyte samples, are discussed to reveal the effect of electrolyte matrix on charge-discharge behavior of a 40 cm 2 cell operated with 1.6 M V 3.5+ electrolytes in sulfuric and hydrochloric acids. Provided that the total vanadium concentration and the conductivity of electrolytes are comparable for both acids, respective energy efficiencies of 77% and 72¨C75% were attained at a current density of 50 mA£¿cm £¿2. All electrolytes in the oxidation state V(V) were examined for chemical stability at room temperature and +45 ¡ãC by titrimetric determination of the molar ratio V(V):V(IV) and total vanadium concentration. View Full-Tex
%U https://www.mdpi.com/2313-0105/5/1/13