Impedance monitoring of fuel cell stacks

Abstract

This paper presents an innovative, electrochemical impedance method for monitoring of electrochemical behaviour of a multi-cell, direct methanol fuel cell (DMFC) device. This method not only provides classical voltage changes at successive cells but also allows their detailed impedance behaviour to be presented. Impedance characteristics of individual cells within a fuel cell stack (depending on actual operating conditions) are obtained via numerous electrochemical tasks, including simultaneous determination of each cell's impedances, performance optimization of the fuel cell stack and effective detection of faulty cells within the stack. The above concerns in situ conditions. The effectiveness of the present method was studied here on a seven-cell, commercially made DMFC stack. In order to effectively detect faulty cells, selected experiments were carried out with insufficient amount of oxygen supplied to a cathode input (ca. 25 % of optimal oxidant dose was used).

Methanol Sensor-Less Control Strategy for Direct Methanol Fuel Cell Startup

“…Effect of V set on Startup Time and Energy Efficiency V set is another key parameter to improve the startup process. It also needs to be limited within a certain range to safely operate the stack (Slepski et al, 2014). Here, a voltage range of 0.4-0.5 V cell −1 is chosen to investigate the effect of V set on startup time and energy efficiency.…”

Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements

“…Due to the introduction of an additional variable component in the current signal, it is possible to simultaneously monitor the voltage and instantaneous impedance spectra during the variable load of the fuel cells. The DEIS method has been successfully used to identify malfunctioning cells in fuel cell stacks [39,40] and also for selecting the optimal conditions of the fuel cell operation [41,42].…”