Report on Gordon Fuel Cell Conference

I attended the 2014 Gordon Research Conference (GRC) on Fuel Cells in August. For those of you not familiar with Gordon conferences, I will make a plug for them as a great venue for learning much detail and interacting closely with many of the major contributors in a specific field. GRC has a wide variety of topics covered (see website link for 2015 meetings: http://www.grc.org/meetings.aspx?year=2015). They are limited to ~150-250 attendees and there is generally only one session running. They also tend to organize the schedule to allow large chucks of “down time” to provide lots of opportunity for informal interactions.

Partly, I wanted to attend this year’s fuel cell conference to see how the area is fairing after having gone through a near-death experience at the end of the last decade (at least from a US federal funding standpoint). It seems that things are looking a bit brighter these days. Many of the academic researchers are moving more solidly into the fuel cell area (or calling their “redox flow battery” research fuel cells again). I am also interested to see the state of understanding of transport phenomena (water, oxygen and protons) in ultra-thin films of the polymer used in PEM fuel cells (perfluorosulfonic acid or PFSA, aka Nafion®). I described my interest in this area in a previous post (https://trace-bmps.org/blog/funding/2014/04/07/concept-for-proposal-to-nist).   It turns out there are several groups working in the area of trying to quantify and understand on transport properties change relative to bulk ones for polymer films on the order of ~50 nm or thinner.

NIST: Kirt Page (part of Functional Materials group in the Materials Measurement Lab) presented work they have been doing using various exotic X-ray and neutron scattering techniques to track water uptake as diffusion in PFSA films coated on silicon wafers. They have found that the water diffusivity through the film drops by orders of magnitude as the film thickness drops below ~100 nm. They also did some elegant measurements of the free space fraction in the polymer film using Positron Annihilation Lifetime Spectroscopy (PALS) which shows a much tighter packing of the polymer chains in these thin films. The films are generally referred to as “confined” meaning the polymer chains are interacting with the substrate more strongly than they would in the case of a thicker or bulk case. Kirt is part of the group that I had originally approached last spring to see about submitting a proposal to NIST. Unfortunately, the way NIST is organized, each group can either choose to use all their budget internally or allocate some to outside proposals. The Materials Measurement Lab tends to have all their budget focused on internal work, so there is no opportunity for me to write for a grant there.

Adam Weber (Lawrence Berkley Nat’l Lab): Adam is an up and coming figure in the fuel cell area and has been doing work in the ultra-thin PFSA film area also. He has focused recent work on looking at the water uptake properties of films supported on different substrates (silicon, carbon, platinum, gold). He found that the interaction is much stronger for platinum and gold compared with carbon.

Mike Hickner (Penn State) Mike is a former student of the “other” Jim McGrath from Virginia Tech., who has a tremendous reputation in the polymer science field. Sadly, he recently died after a long battle with brain cancer. Mike has been working mostly in membrane development for Alkaline Fuel Cells, specifically looking at chemical stability. I spoke with him at one breakfast about the work I’m thinking of and he advised that oxygen permeation measurements are tricky because of issues with oxygen leaks into the system can confuse the permeation results. He thought it might be smart to put the permeation device within a secondary vessel that is purged with Ar or N2 to minimize this effect. He also thinks that the transport properties are likely heavily influenced by the substrate (as Weber showed) and even whether a potential is applied.

Kunal Karan (University of Calgary) Kunal has been doing interesting work in collaboration with these other folks wherein his group has created self-assembled layers of PFSA down to thickness of a couple nm by soaking substrates in dilute solutions of the PFSA. They had a post showing some TEM work with the film supported on lacy carbon. He offered to coat some of our pnc-Si membranes if I was interested. This may be a good approach for very thin (i.e. <10 nm), where spin coating may not provide very uniform films.

Karren More (Oak Ridge Nat’l Lab) Karren is one of the best electron microscopists in the world and has been doing TEM with fuel cell materials for the past ~10 years in collaboration with other DOE labs and universities. Her talks are often sprinkled with controversy and drama because she finds things that don’t agree with the electrochemists’ model of how they think the fuel cells work. She, in turn, has no difficulty in telling the electrochemists that they are simply wrong, generally in a somewhat dismissive manner. She had some interesting results of various carbon-supported platinum catalysts showing that there are <10 nm pore structures within the particles for some of the carbon types, which has many implications for how effectively available the platinum particles are if they are within these pores rather than on the outside surface of the ~20-40 nm carbon particles. At one point, she showed a slide with a picture of one of SiMPore’s pnc-Si TEM grids that had been coated with a thin layer of PFSA by folks at General Motors. I got contact information from her later and will get in touch with the fellow at GM to see how they made the coatings.

Beyond the area of thin PFSA films, there were a couple of other interesting talks and interactions I had:

Stephan Marsh of Encite LLC talked about PEM fuel cells on a chip. His company is using MEMS techniques to make short, cylindrically shaped fuel cells of ~100 µm diameter, where the electrodes are on the inner and outer surfaces. The concept in principle is intriguing, but of course there are a zillion pesky details.  One idea is to “print” a bunch of cells and attach them with switches that enable one to go between series operation (higher voltage, low current) and parallel (low voltage, higher current).  I think there are some interesting possibilities for low power devices.  He seemed to overstep a bit when he tried to show that by scale up, one could get to power densities approaching 10 kW/L and implied that this would be a viable manufacturing technique for automotive.  The main issue is that his design shows no means for heat rejection other than convective air cooling, which at 10 kW/L power density would lead to a very bad end.  He kept emphasizing Moore’s Law and seemed to think that fuel cells could readily hitch a ride on the huge growth rates enjoyed by semiconductor industry development of transistor miniaturization.  His command of electrochemistry is unfortunately almost non-existent, so I fear he has many steep learning curves ahead of him.

Calum Chisholm (SAFcell):  I met Calum at dinner and talked with him several other times. He is a materials science graduate from Cal. Tech. who went on to found SAFcell based on a solid acid electrolyte material that he developed in his Ph.D. The material is a simple cubic structure of cesium with phosphate groups at the center of each cube (CeH2PO4). Once, heated above 230 °C it undergoes a phase transition that results in 1000-fold increase in the proton conductivity. The material is a lot cheaper that PFSA, and by operating at high temperature, the anode is much more tolerant of contaminants. The power density is never likely to approach that of PEM fuel cells, but it is an intriguing technology for stationary. I also talked with Alex Papandrew or U. Tenn. who got his Ph.D. in the same group as Calum and went on to work at SAFcell for a few years before going to UT. He shared the presentation he made two years ago at the Gordon conference on the SAFCell technology. There might be some possible application of the NPN membrane as a scaffold to enable thinner membranes with their solid acid electrolyte material.

The final talk of the week was by Nate Lewis of Cal. Tech.’s dept. of chemistry. He also heads the U.S. Department of Energy Innovation Hub on Joint Center for Artificial Photosynthesis, to develop methods to generate fuels directly from sunlight. He has been giving this same talk all over (http://nsl.caltech.edu/energy) where he outline the present crisis regarding energy use and related climate implications and then outlines the various carbon-neutral options. The talk is rather sobering in terms of the magnitude of the issue that the planet faces over the next couple decades – particularly in face of our country’s lack of a coherent energy policy.