Electrolyte Influence on Iron-Ion/Hydrogen-Ion Redox Flow Battery

In the iron-ion/hydrogen redox flow cell, the redox flow battery electrolyte concentration has dramatic impact on the battery charging performance and OCV. Although chloride salt has greater charge carrying capacity per gram of salt in comparison to those of sulfates, optimal mixture of these electrolytes can yield a much higher battery performance than either electrolyte alone. The influence of electrolyte concentration on cell performance is investigated and the results will be presented. Charge polarization of the Fe²⁺ to Fe³⁺ was investigated using single and multiple electrolyte mixtures on both glassy carbon and platinum electrodes. Typical cyclic voltammograms obtained from FeCl₂, FeSO₄ and NH₄FeSO₄ and their mixtures are shown in Fig 1.