Fuel cells have been five years away from mass commercialization for more than 40 years – it’s a perennial ‘technology of the future’. Over that time, funding for fuel cell research has gone through several boom-bust cycles. I started my research career studying solid oxide fuel cells during one ‘boom cycle’ – and then a bust in funding redirected me to materials characterization.

Despite the change in my career focus, I still watch the fuel cell industry with keen interest. Why? Fuel cells have tremendous potential to transform the energy landscape – from powering electric vehicles that need fast refueling to enabling localized power generation. When using hydrogen as a fuel, the only waste product is water. And even when using hydrocarbon fuels such as natural gas or methane, fuel cells are greener than conventional alternatives. They generate fewer greenhouse gases, and those gases are easier to capture before they reach the atmosphere.

Poised for success

So, what makes the current ‘boom cycle’ different than the ones before? Well, for many years, the limiting factor has not been the fuel cells themselves, but the production of hydrogen fuel. Electrolysis, the traditional method, uses a lot of electricity, which negated the environmental and economic advantages of fuel cells. But in the past five years, a boom in renewable energy production has opened new possibilities.

In some parts of the world, renewable energy is producing more electricity than can be used. For instance, China produces 150 GW of excess electricity from renewable energy. Because this electricity cannot be integrated into the grid, it is lost. In Europe, the northern Netherlands and the Orkney Islands produce more tidal and wind power than they can consume. This surplus energy can be used to cheaply produce hydrogen as an energy storage fuel. The hydrogen is easily transported, via shipping or pipeline, to places where it can power electric vehicles.

What’s more, natural gas production has increased in the United States. This could enable electricity production in fuel cell generators in residential neighborhoods and business districts. The lack of moving parts and industrial pollution makes fuel cells ideal for these areas. Generating electricity locally would greatly reduce the amount lost in transmission through power lines. In this way, it’s more economical, more efficient, more environmentally friendly, and more robust against natural disasters. And I don’t think anybody will miss seeing ugly power lines scattered across the landscape.

Where we fit in

With renewable fuel production made easier, one of the greatest remaining hurdles is scaling up production while maintaining control of catalyst layer thickness and the distribution of precious metal catalysts. This is where I get excited – because Malvern Panalytical’s technology portfolio is perfectly matched to the needs of proton exchange membrane fuel cell (PEMFC) manufacturing.

Characterizing catalytic inks

For instance, catalytic inks are key to balancing the cost, performance, and durability of PEMFCs. And characterizing these inks is essential to optimize and monitor their deposition on the fuel cell membrane or gas diffusion layer. Four Malvern Panalytical technologies work together to provide this comprehensive analysis, all with the proven potential to be scaled up for mass production:

  • X-ray diffraction to confirm the nanocrystallite size of the Pt catalyst.
  • X-ray fluorescence to determine the chemical purity and composition of the catalyst.
  • Laser diffraction to confirm the particle size and dispersion of the Pt-on-C catalyst.
  • Dynamic light scattering to measure zeta potential to evaluate ink stability.

Most characterization is done using routine methods, but our mad scientists also perform unconventional analyses. For example, Paul Carpinone used the Mastersizer 3000 to monitor aggregate size as a function of time during shear dispersion. This can be used to determine the optimal parameters to avoid under-dispersion or over-dispersion. And I have used a variation of the K-factor technique for amorphous quantification to devise a method to estimate catalyst loading in the ink, using the Aeris compact X-ray diffractometer.

Figure 1 The Mastersizer 3000 laser diffraction system measured particle size over time during dispersion under shear. This information helps optimize catalyst dispersion in the ink for manufacturing.
Figure 2. The Aeris benchtop X-Ray Diffractometer measured nanocrystallite size and peak intensity of powders with different levels of Pt loading on Vulcan XC72 carbon support.  Advanced analytical techniques estimate the catalytic loading from the total scattering intensity.

Optimizing polymer membrane properties

The polymer membrane must also be evaluated before and during processing. Under the heat and stress of manufacturing, the membrane loses essential water content and may crystallize. Our Empyrean diffractometer can monitor the degree of crystallinity using wide-angle X-ray scattering (WAXS). Changes in free water content can also cause shrinkage and swelling cycles in the membrane and, ultimately, failure. Using near-infrared spectroscopy (NIR), our LabSpec can monitor these free water content changes to prevent this.

Figure 3. The LabSpec Near-Infrared spectrometer measured the amount of free water in pristine Nafion (green) and loss of free water in heat-treated Nafion (red).

Analyzing electrode thickness

High-rate measurement methods are also crucial in determining the thickness and distribution of the catalyst during manufacture – as identified by the US Department of Energy [Wheeler and Sverdrup, Technical Report NREL/TP-560-41655]. And, at Malvern Panalytical, we’ve developed several in-line and off-line tools for these measurements.

For instance, our Insitec laser diffraction system provides in-line monitoring of particle size dispersion in the ink. At the same time, photon sensor and microcalipar technology, co-developed with our sister company NDC, provides in-line layer thickness monitoring. And don’t forget high-throughput XRF and XRD for evaluating the dispersion’s uniformity off-line. What’s more, a colleague and I may even have discovered an in-line process to monitor catalytic loading. Indeed, we’re eager for partners to test this new method and help us validate it…

And even more…

For those of you who lost count, that’s 12 out of our 21 characterization technologies that can add value to PEMFC manufacturing. But wait, there’s more! Our Process & Automation Solutions unit can integrate this equipment into process lines with minimal disruption, and our Data Science Team can use advanced machine-learning analytics to integrate all these analyses into a comprehensive monitoring solution. This all goes to show that you never know where life may take you. Although I left the field of fuel cell research years ago, I now find myself part of a company making valuable contributions to fuel cell commercialization. With these technologies, we’re getting closer and closer to that goal – and to a new world of energy production.

The production PEMFC’s is scaling up already. The analysis of catalytic inks can improve the performance of these fuel cells and help scale-up mass production. During a webinar, hosted by Plugvolt, I will go into the characterization of this key component.

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