The development of economical hydrogen-production methods is essential to establishing hydrogen as a viable fuel. One promising method of hydrogen production is proton-exchange-membrane water electrolysis (PEMWE), where water is converted electrochemically to hydrogen and oxygen gas. The PEMWE research efforts are multi-faceted and aim to improve material costs, operations costs, and safety, which require robust methods to accurately gauge PEMWE cell performance. Electrochemical cells can be fundamentally characterized in terms of a Tafel equation, which describes the relationship between the faradaic current density and applied potential as a log—linear relationship, respectively. Due to the complex and highly coupled chemistry and physics within the membrane—electrode assembly, the operational ranges of experimental PEMWE data used to extract Tafel parameters are often nebulous, which results in addition of a human element in estimating the appropriate data where a Tafel-kinetic model is assumed to be applicable.

In this work, an algorithm for extracting the Tafel slope was developed to assess the adherence of polarization data to a Tafel-kinetic model. The method was developed using experimental PEMWE data and is a systematic and statistical assessment that uses error propagation and Monte-Carlo simulations of fitted parameters to yield 95% confidence intervals (CIs). As shown in Figure 1a, the CIs are used to identify operational ranges where polarization data is consistent with a Tafel-kinetic model. The method was used to perform a voltage-breakdown analysis, which is shown in Figure 1b. A voltage-breakdown analysis is an analytical tool where voltage losses are quantified and associated with a specific mechanism, such as mass transfer, ohmic resistance, kinetics, and thermodynamics. The algorithm was implemented in a portable and open-source format, which was shown to reduce variability of analyses performed by members of the H2NEW consortia. Applicability of the algorithm should be transferrable to other electrochemical systems and may serve as a standardized method of extracting electrochemical kinetic parameters and performing voltage breakdown analyses.

Acknowledgements

This research is supported by DOE Hydrogen and Fuel Cell Technologies Office, through the H2NEW Consortia.