Evaluation of Selected Anode and Cathode Gas Diffusion Layers for Use in PEM Water Electrolysis with Focus on Compatibility with 3M's Ir-Nstf Based Electrolyzer Catalyst Coated Membranes

Abstract

The interest in harnessing energy from renewable sources to achieve environmental cleanliness in the energy industry keeps gaining momentum. The need to be able to convert and store all that renewable energy has rekindled interest in hydrogen as a clean and environmentally benign energy carrier. Likewise, the rising star of hydrogen enabled mobility (motive fuel cells) ads further impetus to addressing needs for economical means to generate hydrogen - the ultimate key to success for hydrogen as fuel in societal everyday transportation solutions. Polymer Electrolyte Membrane (PEM) water electrolysis emerged recently as one of the better choice today to address the need for hydrogen fuel by virtue of being compatible with highly variable and unpredictable nature of the renewable energy generation. Even though PEM has in fact been used for quite a few years now without undergoing substantial improvements over those years now, however, with the new focus on hydrogen as the energy carrier there is much more interest in low cost/high efficiency H2 production. There are two main ways to lower the cost of hydrogen production via PEM water electrolysis: to lower the capital expenses (CAPEX) and/or to lower the operating expenses (OPEX). We at 3M have recently demonstrated a way to address reducing the high CAPEX by widening the range of current densities where electrolyzers can operate from a maximum of about 2.0 A/cm2, as used today in commercial electrolyzers, to as much as 20 A/cm2 by employing a novel 3M’s proprietary Nano Structured Thin Film (NSTF) catalyst and more conductive 3M PFSA based electrolytes in the electrolyzer MEA1-3. What the cited work does not touch upon is the need to further address high electrolyzer CAPEX by lowering costs of individual components of electrolyzer cells. This could be done independently of the operational cost savings and in addition to them. One such area where improvements can still be made is in the use of more economical Gas Diffusion Layers. These differ in function from fuel cell GDLs by the fact that reactants move through them in different directions, the requirements for performance, durability and mechanical robustness are also much more stringent. The standard materials in use as GDLs today are based on sintered titanium plates and although they work well and perform satisfactory such GDLs are neither inexpensive nor are they compatible with high speed/low cost roll-to-roll manufacturing – a necessary requirement for substantial cost reductons. In this work, we intend to present results of our attempts to investigate materials available in the fuel cell realm for compatibility and performance in electrolyzer cathodes as possible replacement for Ti sinters. We will also present data evaluating alternatives to rigid Ti sinters for electrolyzer anodes. All materials are selected such that compatibility of these candidate GDL materials with high speed/low cost roll-to-roll manufacturing process is not negatively affected by their properties and/or modifications. Krzysztof A. Lewinski, Sean M. Luopa, (invited) “High Power Water Electrolysis as a New Paradigm for Operation of PEM Electrolyzer” (abstract 1948), Spring ECS Meeting, Chicago, IL, May 2015. Krzysztof A. Lewinski, Dennis van der Vliet, and Sean M. Luopa, “NSTF Advances for PEM Electrolysis - the Effect of Alloying on Activity of NSTF Electrolyzer Catalysts and Performance of NSTF Based PEM Electrolyzers” ( 1457), Fall ECS Meeting, Phoenix, AZ, Oct 2015. Krzysztof A. Lewinski, Dennis van der Vliet, and Sean M. Luopa, “NSTF Advances for PEM Electrolysis - the Effect of Alloying on Activity of NSTF Electrolyzer Catalysts and Performance of NSTF Based PEM Electrolyzers”, (10.1149/06917.0893ecst), ECS Transactions, 69 (17) , p. 893-917 (2015).