About this Research Topic
The development of zero-carbon emission electrochemical energy conversion technologies such as fuel cells as promising alternatives to energy production by fossil fuels has tremendously attracted interests in recent years. However, fuel cells are complex multi-scale systems and multi-physics systems, with processes occurring at drastically different rate – such as ion transport, gas diffusion, anodic and cathodic kinetics, to name a few – yet all influencing the electrochemical performances. One of the key techniques to reveal the influence and contribution of individual processes is impedance spectroscopy, which can be carried both in operando and in specific atmospheres.
Electrochemical impedance spectroscopy can be insightful for the characterization of performances in devices, from the intrinsic properties of the catalysts properties, gas diffusion mechanisms and electrolyte conductivity, to the influence of the operating temperature, flow rate and pressure, and also to determine the strength and weaknesses of new designs. Electrochemical impedance spectroscopy is also an invaluable diagnostic tool to analyze degradation mechanisms as it can detect the changes in kinetic mechanisms over time. Furthermore, it is also very useful for the analysis of localized mechanisms for instance when coupled with current mapping. In ceramic based cells, the influence of microstructural features on cell performance can be effectively probed, determining the bulk and grain boundary contributions to overall cell resistance.
As impedance results can be often challenging to analyze, three main approaches have emerged to facilitate its interpretation, using equivalent circuit modelling, analytical/physical based modelling and more recently the model-free distribution of relaxation times approach. Finally, new impedance spectroscopy techniques have emerged in recent years inspired by electrochemical impedance spectroscopy, capturing the sinusoidal response of the temperature, water and of other variables of interest to a current density or voltage perturbation over a frequency range.
This Research Topic welcomes studies introducing new concepts and recent progress in impedance spectroscopy from all avenues of fuel cells, such as polymer electrolyte membrane fuel cells (low and high temperature) (PEMFCs), solid oxide fuel cells (SOFCs), direct methanol fuel cells (DMFC), alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFCs) and finally molten carbonate fuel cells (MCFC).
Both original research articles and review articles on impedance spectroscopy of fuel cells are highly and warmly welcome.
The Research Topic covers a wide range of topics in the field of impedance spectroscopy of fuel cells, including, but not limited to:
• Performance characterization
• Design optimization
• Low-frequency impedance
• Degradation analysis
• Equivalent circuit modelling
• Analytical modelling
• Distribution of Relaxation Times
Keywords: Fuel Cells, Electrochemical impedance spectroscopy, Diagnostics, Degradations, Analysis and Modelling
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