Fuel cell performance is determined by the complex interplay of mass transport, energy transfer and electrochemical processes. The convolution of these processes leads to spatial heterogeneity in the way that fuel cells perform, particularly due to reactant consumption, water management and the design of fluid-flow plates. It is therefore unlikely that any bulk measurement made on a fuel cell will accurately represent performance at all parts of the cell. The ability to make spatially resolved measurements in a fuel cell provides one of the most useful ways in which to monitor and optimise performance. This Minireview explores a range of in situ techniques being used to study fuel cells and describes the use of novel experimental techniques that the authors have used to develop an 'experimental functional map' of fuel cell performance. These techniques include the mapping of current density, electrochemical impedance, electrolyte conductivity, contact resistance and CO poisoning distribution within working PEFCs, as well as mapping the flow of reactant in gas channels using laser Doppler anemometry (LDA). For the high-temperature solid oxide fuel cell (SOFC), temperature mapping, reference electrode placement and the use of Raman spectroscopy are described along with methods to map the microstructural features of electrodes. The combination of these techniques, applied across a range of fuel cell operating conditions, allows a unique picture of the internal workings of fuel cells to be obtained and have been used to validate both numerical and analytical models.
This review discusses the range of diagnostic techniques reported in the literature for spatially resolved studies of operating fuel cells. In situ diagnostic techniques continue to reveal more about the working of fuel cells and in so doing allow for improved cell hardware design, materials selection, and choice of operating conditions to realize advanced electrochemical performance and longevity. These techniques also allow us to scrutinize the validity of conventional bulk electrical measurements and develop detailed models of fuel cell operation.
This article is categorized under:
Fuel Cells and Hydrogen > Science and Materials
Piezoelectric crystal microbalance devices based on gallium orthophosphate (GaPO 4 ) have recently become commercially available. This material allows for operation at over 900 °C and therefore has potential as an analytical technique for the study of surface reactions at high temperatures. This paper describes preliminary work to assess the suitability of this technology for such applications. Change in oscillation frequency associated with temperature and gaseous environment is studied, and the ability to detect coke formation on a Ni-modified crystal is demonstrated. These results suggest that the technology can be developed as a low cost, high sensitivity gravimetric sensor for monitoring surface processes in high temperature chemical reactors such as reformers and solid oxide fuel cells (SOFCs)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.