PEMFC Stack Diagnostics Using EIS

Abstract

One way of improving the durability and reliability of a fuel cell stack or system is to isolate faults within the fuel cell and perform targeted condition-based maintenance on the affected components, to remove or limit the conditions that caused the fault. This can be done by on-line monitoring of the fuel cell system's state of health to locate and isolate faults and prevent sudden failures before they occur and correcting faulty conditions to prolong the lifetime of the fuel cell. This paper presents electrochemical impedance spectroscopy (EIS) results obtained on PEMFC stacks, with the aim of investigating the fuel cell stacks’ response to different faults, for a possible use of EIS as an advanced monitoring and diagnostics tool. The stacks used in this study are from Dantherm Power A/S, intended for stationary microCHP application. Four different faults were considered; change in fuel composition, air starvation, fuel starvation and water management, both for flooding and drying. Each fault simulation was performed in a separate fuel cell stack to avoid the mixing of the impedance signatures of the different faults. The same continuous, steady state operations under nominal condition were recorded prior to fault simulations as healthy-state references. Then the different faults were induced at varying current densities and varying fault levels.