Abstract
The use of clean hydrogen around the world is expected to significantly increase in the coming decades as various countries move towards their carbon neutral goals. The United States has committed significant funds ($9.5 Billion over the next 5 years) to the demonstration of a clean hydrogen infrastructure with electrolysis ($1 Billion in research over the next 5 years) being one of the key enabling technologies. Polymer electrolyte membrane water electrolyzers (PEMWE) for hydrogen production are expected to play a critical role in this transition to a hydrogen economy. The DOE has formed a consortium (H2NEW : Hydrogen from the next generation of electrolyzers of Water) to overcome technical barriers to affordable, reliable and efficient electrolyzer development. The consortium is working on various aspects of PEMWEs to improve their durability, decrease their cost, improve manufacturability and demonstrate economic feasibility. As part of this effort, the consortium is developing accelerated stress tests (ASTs) for PEMWEs. The DOE in collaboration with National Laboratories and the U.S. Drive Fuel Cell Technical team has developed a set of validated and widely accepted ASTs for fuel cells. While these fuel cell ASTs have spurred significant materials development over the past decade, there is no accepted set of ASTs for PEMWEs.
This talk will summarize our recent learnings from the development of PEMFC ASTs and how these apply to PEMWEs. While several materials including the cathode catalyst, membrane, and cathode gas diffusion layer are similar between these two systems, there are significant differences in the operating conditions and materials used at the anode of the electrolyzer. The key to successful AST development is to ensure that the stressors accelerating the degradation mechanisms are relevant to the operating conditions encountered in the intended application. An AST working group (ASTWG) that includes various U.S. electrolyzer manufacturers has been established within the consortium to incorporate feedback from commercial electrolyzer systems. Literature reports have demonstrated that both potential cycling1 and transition through Ir/IrOx redox potential2 (during open circuit operation or shutdown of electrolyzer) can be detrimental to the anode catalyst. Membrane degradation occurs under electrolyzer conditions and is accelerated with increasing temperature and low current density operation.3 The effect of electrolyzer operating conditions on both membrane and anode catalyst durability will be discussed in this talk. The various stressors leading to increased degradation of both anode catalysts and membranes will be discussed and potential PEMWE ASTs will be proposed.
Acknowledgement
This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the H2NEW consortium.
References
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