Modeling of dynamic behavior of vanadium redox batteries (VRB) with contamination properties of proton exchange membrane

Vanadium redox flow batteries (VRB) represent a promising technology for a storage medium suitable for matching the intermittent output of renewable energy systems (RES) to the changing requirements of an electricity grid [1]. In a typical VRB, the proton exchange membrane (PEM) separates two compartments (positive and negative), each filled with vanadium sulfate in dilute sulfuric acid [2]. The function of the PEM is to allow proton flow, and to prevent the flow of other cations - specifically vanadium ions, which are present in the electrolyte solution on both sides of the PEM. In practice, however, existing PEMs have only limited cation selectivity, and this property influences the dynamic behavior of the battery and its energy efficiency. The present paper models VRB dynamic behavior including the presence of contaminants in the electrolytes. Coupled differential equations for the various ion flows were solved numerically using the Simulink subroutine of MATLAB and compared with a series of measurements performed on an actual VRB.