The reference solutions of the four vanadium electrolytes were prepared by electrochemical charging of an equimolar V III /V IV commercial solution (Oxkem Limited, UK) with a vanadium concentration of 1.82 M and an acid concentration of 4.6 M. A key advantage of this preparation method, as detailed in our previous work, lies in the use of spectrophotometric titration with real-time spectral monitoring. This approach enables the precise identification of inflection points in the absorbance data, thus facilitating the accurate detection of pure electrolyte solutions . Additionally, we also employed this titration approach to verify the total vanadium concentration (1.82 M) of the commercial electrolyte using Potassium Permanganate as titrant .