Multichannel Electrochemical Impedance Spectroscopy and equivalent circuit synthesis of a large-scale vanadium redox flow battery

An original multichannel Electrochemical Impedance Spectroscopy (EIS) system operating at high bias current and suitable for kW-class Vanadium Redox Flow Batteries (VRFBs) is presented. Power signal connections, whose stray parameters affected measurements, required a careful optimization calibration in the implementation of measurement chain. In any cases, electromagnetic interferences set an upper limit to applied stimulus frequency that limited data each point. The paper provides early results obtained with this EIS system, which were used identify equivalent circuit whole stack cell represented dynamic Thévenin equivalent, i.e. series voltage source, variable resistor RC loop. dependence on conditions has been experimentally analyzed, confirming only RC-loop resistance strongly by mass transport. To our knowledge, first validated against measurements taken real industrial-scale VRFB. Building methodology here presented, advanced online state health industrial flow batteries can be developed implemented. • A novel kW-scale RFBs Stray power connections affecting tackled. lumped was identified means measurements. analyzed. analyzer adopted procedure SOH evaluation RFBs.