Capabilities

Capabilities

Multicomponent Ink Development, High-Throughput Fabrication, and Scaling Studies

Laboratory

National Renewable Energy Laboratory (NREL)

Capability Expert

Michael Ulsh, Scott Mauger

Class

Benchmarking
Characterization
Process and Manufacturing Scale-Up

Node Readiness Category

1: Low-Temperature Electrolysis (LTE)
2: Photoelectrochemical (PEC)

Description

Previous capability name: "High-Throughput Approaches to Scaling New PEM Electrolysis Electrodes Using Relevant Production Technologies."

Catalyst integration with electrode and cell materials, high-throughput fabrication, and scaling studies are recognized core competencies at NREL. We have been working on optimizing inks for new catalysts and electrode layers for several years. We have the equipment, expertise, and methodologies to formulate and fabricate these multicomponent inks, study the effects of catalyst and support composition, ionomer type, solvent, and mixing parameters, and characterize both the micro/nanoscale colloidal properties and the macroscale fluid properties of the inks via light scattering, static and dynamic contact angle, zeta potential, and steady and oscillatory shear rheology (Figure 1). We have also developed and implemented small-scale processing capabilities for fabricating catalyst coated membrane- and gas diffusion electrode-style cells (Figure 2) FCTO-funded capabilities include ultrasonic spraying (Figure 3), knife, bar and rod coating. However, we can leverage other NREL-internal capabilities such as inkjet and aerosol spray (Figure 4), and slot die sheet coating (Figure 5).

Given an understanding of ink properties and process parameters at a small scale, we can then use a multi-technology roll-to-roll (R2R) coating station with multiple coating technologies (slot die and gravure) to perform high-throughput fabrication of electrodes and extend our understanding of material-structure-process relationships to scalable processes. This high-throughput capability enables many-meters-in-length production of electrodes of different composition, and comparison of the process parameters and resulting electrode structures based on several types of relevant deposition processes.

NREL’s capability is not only relevant to PEMEC systems, but also to AEM, PEC, and SOEC systems. Proven protocols and methodologies developed for PEM systems can be leveraged for  these newer or less-studied systems. In addition, NREL’s capability is being leveraged under the ElectroCat EMN for PGM-free catalyst systems and electrodes, showing relevance to those related material sets.

Capability Bounds‎

For ink formulation research only small amounts of materials are needed, e.g. 100 mg of catalyst can be used for Zeta potential and dynamic light scattering measurements of many different formulations. Rheology measurements require a few hundred milligrams of material. Small-scale electrode fabrication requires a few hundred milligrams of material. NREL’s current capability enables many-meters-in-length production of electrodes of different composition, and comparison of the process parameters and resulting electrode structures based on several types of relevant deposition processes. R2R coating experiments require grams of catalyst or ionomer materials. These are all laboratory-scale capabilities with no pertinent bounding limitations.

Unique Aspects‎

These capabilities reflect NREL’s core competencies in process science, electrode integration, and scale-up. The breadth and scale of deposition capabilities as well as capability experts’ background in industrial R2R processing and colloid science is unique.

Availability‎

There are no pertinent use limitations. Some of the capabilities are in the NREL Energy Systems Integration Facility, a user facility where external researchers can apply for access to facilities and equipment.

Benefit‎

Development of electrode compositions and structures has traditionally followed a very linear pathway. However, extending the high-throughput and combinatorial thrusts of HydroGEN to PEM electrolysis electrode development will require different capabilities than the discovery and synthesis aspects of the catalyst materials themselves. Capabilities and methodologies are required to fabricate electrodes on relevant substrates and using relevant processes in ways that enable high-throughput evaluation of matrices of electrode compositions and structures. This would enable accelerated evaluation of electrode ink composition and properties as well as process parameters for optimal uniformity, performance and durability. In addition, a goal of HydroGEN is to advance catalyst and electrode scale-up and lower component costs at high volume production. The proposed capabilities are highly relevant to understanding and advancing high-volume production of PEM electrolysis electrodes and cells.

Images

Figure 1. a) Zeta potential measurements of IrOx and Pt on Vulcan carbon showing similar increase in electrostatic stability with addition of ionomer. b) Steady-shear rheology of IrOx catalyst compared to Vulcan carbon. Like carbon blacks, e.g. Vulcan, IrOx shows rheological properties of an agglomeration. c) Steady-shear rheology of IrOx catalyst as a function of ionomer:catalyst mass ratio. The transition from shear thinning (I:C = 0) to Newtonian (I:C > 0) shows that the ionomer is stabilizing the particles against agglomeration.

Figure 2. Small-scale Mayer rod coating of IrOx catalyst layers. The photo at left shows highly uniform electrodes are produced with this method. The plot at right shows a wide range of loadings are possible from the same ink formulation using different coating rods.

Figure 3. Ultrasonic spray system fabricating multiple electrodes.

Figure 4. Aerosol jet spray system.

Figure 5. Multitechnology coating station with slot die and microgravure coating ability, two oven sections and interleaf peeler.

References‎

M. Ulsh, S. Mauger, K.C. Neyerlin, “Material-process-performance relationships for roll-to-roll coated PEM electrodes,” poster presentation at the Annual Merit Review, Washington, DC; June 2017.

M. Ulsh, S. Mauger, K.C. Neyerlin, D. Wood, J. Li, M. Wood, K. More, D. Myers, N. Kariuki, J. Park, C.F. Cetinbas, R. Ahluwalia, G. Krumdick, A. Weber, F. Ma, R. Prasher, “PEM Fuel Cell Gas-diffusion Electrodes with Ionomer-rich Surface Layer,” poster presentation at the AMO Peer Review; Arlington, VA; June 2017.

S. Mauger et al., “Material-process-performance relationships for roll-to-roll coated fuel cell electrodes,” oral presentation IO1B-1441 at the Fall ECS Meeting; National Harbor, MD; October 2017.

S. Mauger et al., “Rheological characterization of interparticle interactions in fuel cell catalyst dispersions,” oral presentation IO1A-1382 at the Fall ECS Meeting; National Harbor, MD; October 2017.

S. Khandavalli, S. Mauger, J.J. Stickel, K. Hurst, K.C. Neyerlin, M. Ulsh, “Rheological properties and interparticle interactions of fuel cell catalyst dispersions,” poster presentation at the Society of Rheology Meeting; Denver, CO; October 2017.