Fuel cells have not been particularly known for their practicality and affordability, but that may have just changed. There&rsquo;s a new cell that runs on cheap fuel at temperatures comparable to automobile engines and which slashes materials costs.Though the cell is in the lab, it has high potential to someday electrically power homes and perhaps cars, say the researchers at the Georgia Institute of Technology who led its development. In a&nbsp;<a href="https://www.nature.com/articles/s41560-018-0262-5" target="_blank">new study in the journal Nature Energy&nbsp;</a>the researchers detailed how they reimagined the entire fuel cell with the help of a newly invented fuel catalyst.The catalyst has dispensed with high-priced hydrogen fuel by making its own out of cheap, readily available methane. And improvements throughout the cell cooled the seething operating temperatures that are customary in methane fuel cells dramatically, a striking engineering accomplishment.Methane fuel cells usually require temperatures of 750 to 1,000 degrees Celsius to run. This new one needs only about 500, which is even a notch cooler than automobile combustion engines, which run at around 600 degrees Celsius.That lower temperature could trigger cascading cost savings in the ancillary technology needed to operate a fuel cell, potentially pushing the new cell to commercial viability. The researchers feel confident that engineers can design electric power units around this fuel cell with reasonable effort, something that has eluded previous methane fuel cells.<h4>&lsquo;Sensation in our world&rsquo;</h4>&ldquo;Our cell could make for a straightforward, robust overall system that uses cheap stainless steel to make <a href="https://www.mdpi.com/1996-1073/7/7/4601" target="_blank">interconnectors</a>,&rdquo; said Meilin Liu, who led the study and is a <a href="http://www.mse.gatech.edu/people/meilin-liu" target="_blank">Regents&nbsp;Professor in Georgia Tech&rsquo;s School of Materials Science and Engineering.</a> Interconnectors are parts that help bring together many fuel cells into a <a href="https://bioage.typepad.com/.a/6a00d8341c4fbe53ef01b7c760a5ae970b-popup" target="_blank">stack</a>, or functional unit.&ldquo;Above 750 degrees Celsius, no metal would withstand the temperature without oxidation, so you&rsquo;d have a lot of trouble getting materials, and they would be extremely expensive and fragile, and contaminate the cell,&rdquo; Liu said.&ldquo;Lowering the temperature to 500 degrees Celsius is a sensation in our world. Very few people have even tried it,&rdquo; said Ben deGlee, a graduate research assistant in Liu&rsquo;s lab and one of the first authors of the study. &ldquo;When you get that low, it makes the job of the engineer designing the stack and connected technologies much easier.&rdquo;The new cell also eliminates the need for a major ancillary device called a <a href="https://en.wikipedia.org/wiki/Steam_reforming" target="_blank">steam reformer</a>, which is normally required to convert methane and water into hydrogen fuel.Liu, deGlee, co-first author Yu Chen, who is a postdoctoral researcher in Liu&rsquo;s lab, and co-first author Yu Tang of the University of Kansas, <a href="https://www.nature.com/articles/s41560-018-0262-5" target="_blank">published the results of their research on October 29, 2018</a>. Their work was funded by the Office of Basic Energy Sciences and the Advanced Research Projects Agency-Energy (ARPA-E), both in the U.S. Department of Energy. It was also funded by the National Science Foundation&rsquo;s Division of Chemistry.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1571103863712-fc.yu_.sm__3.jpg" style="width: 766px;" class="fr-fic fr-dib">Postdoctoral researcher Yu Chen sets up the new fuel cell in a unit used to test it in Meilin Liu&#39;s lab at Georgia Tech. Credit: Georgia Tech / Christopher Moore&nbsp;<h4>&lsquo;Distributed generation&rsquo;</h4>The research was based on a type of fuel cell with high potential for commercial viability, the <a href="https://en.wikipedia.org/wiki/Solid_oxide_fuel_cell" target="_blank">solid oxide fuel cell (SOFC)</a>. SOFCs are known for their versatility in fuels they can use.If it goes to market, though the new cell might not power automobiles for a while, it could land sooner in basements as part of a more decentralized, cleaner, cheaper electrical power grid. The <a href="https://www.fueleconomy.gov/feg/fcv_PEM.shtml" target="_blank">fuel cell stack</a> itself would be about the size of a shoebox, plus ancillary technology to make it run.&ldquo;The hope is you could install this device like a tankless water heater. It would run off of natural gas to power your house,&rdquo; Liu said. &ldquo;That would save society and industry the enormous cost of new power plants and large electrical grid expansions.&rdquo;&ldquo;It would make homes and businesses more power independent,&rdquo; Liu said. &ldquo;That kind of system would be called distributed generation, and our sponsors want to develop that.&rdquo;<h4>Homemade hydrogen</h4>Hydrogen is the best fuel for powering fuel cells, but its cost is exorbitant. The researchers figured out how to convert methane to hydrogen in the fuel cell itself via the new catalyst, which is made with cerium, nickel and ruthenium and has the chemical formula Ce0.9Ni0.05Ru0.05O2,&nbsp;abbreviated CNR.When methane and water molecules come into contact with the catalyst and heat, nickel chemically cleaves the methane molecule. Ruthenium does the same with water. The resulting parts come back together as that very desirable hydrogen (H2) and carbon monoxide (CO), which the researchers surprisingly put to good use.&ldquo;CO causes performance problems in most fuel cells, but here, we&rsquo;re using it as a fuel,&rdquo; Chen said.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1571103900722-fc.meilin.sm__3.jpg" style="width: 766px;" class="fr-fic fr-dib">Principal investigator Meilin Liu holds up an example of the new, practical, affordable fuel cell in his lab at the Georgia Institute of Technology. Credit: Georgia Tech / Christopher Moore <h4>Making electricity</h4>H2&nbsp;and CO continue on to further catalyst layers that make up the anode, the part of the fuel cell that yanks off electrons, making the carbon monoxide and hydrogen positively charged ions. The electrons travel via a wire -&nbsp;creating the electricity flow -&nbsp;toward the cathode.There, oxygen, which is very electron-hungry, sucks up the electrons, closing the electrical circuit and becoming O2-&nbsp;ions. Ionized hydrogen and oxygen meet and exit the system as water condensation; the carbon monoxide and oxygen ions meet to become pure carbon dioxide, which could be captured.For the energy produced, fuel cell technology creates far, far less carbon dioxide than combustion engines.In some fuel cells, the water in the initial reactions must be introduced from the outside. In this new fuel cell, it&rsquo;s replenished in the last reaction phase, which forms water that cycles back to react with the methane.<h4>Catalysts converge</h4>The new catalyst, CNR, manufactured by research collaborators at the University of Kansas, is the outer layer of the anode side of the cell and doubles as a protectant against decay, extending the life of the cell. CNR has strong cohort catalysts in inner layers and on the other side of the cell, the cathode.On the cathode end, oxygen&rsquo;s reaction and movement through the system are usually notoriously slow, but Liu&rsquo;s lab has recently sped it up to raise the electricity output by using what&rsquo;s called nanofiber cathodes, which Liu&rsquo;s lab developed in a prior study. (<a href="https://www.nature.com/articles/ncomms14586" target="_blank">A tailored double perovskite nanofiber catalyst enables ultrafast oxygen evolution</a>.)&ldquo;The structures of these various catalysts, as well as the nanofiber cathodes, all together allowed us to drop the operating temperature,&rdquo; Chen said.

This could actually become a practical, marketable energy solution. Practical to run at cooler temperatures and on cheap fuel: the new fuel cell in the lab of Meilin Liu at Georgia Tech. Credit: Georgia Tech / Christopher Moore

Fuel cells have not been particularly known for their practicality and affordability, but that may have just changed. There’s a new cell that runs on cheap fuel at temperatures comparable to automobile engines and which slashes materials costs.

A Robust Fuel Cell that Runs on Methane at Practical Temperatures

CHAMPAIGN, Ill. &mdash; Batteries that charge faster and have greater capacity could boost portable electronic devices and electric cars. A new method to simultaneously test stress and strain in battery electrodes gives researchers a window into the mechanical, electrical and chemical forces within lithium-ion batteries. The method revealed an unexpected point of stress in the charging cycle, which could guide development of better batteries.University of Illinois&nbsp;<a href="http://www.chemistry.illinois.edu/" target="_blank">chemistry</a> professor&nbsp;<a href="http://www.chemistry.illinois.edu/faculty/agewirth.html" target="_blank">Andrew Gewirth</a>,&nbsp;<a href="http://www.matse.illinois.edu/" target="_blank">materials science and engineering</a> professor&nbsp;<a href="http://www.matse.illinois.edu/directory/profile/n-sottos" target="_blank">Nancy Sottos</a> and graduate students Elizabeth Jones and Hadi Tavassol published&nbsp;<a href="http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat4708.html" target="_blank">their work</a> in the journal Nature Materials.&ldquo;We are finding limitations that are preventing the material from operating properly,&rdquo; Gewirth said. &ldquo;We are trying to understand what those limitations are and then develop materials and ways of processing materials that overcome them.&rdquo;A lithium-ion battery works by transferring lithium ions between two electrodes: the cathode and anode. When the battery is charged, lithium goes into the anode, which causes the material to expand. When the battery is discharged, the lithium leaves the anode, causing it to contract. However, because the material is constrained within the battery cell, it cannot truly expand and contract as it would when unconstrained, which causes mechanical stress within the material, Sottos said. Most methods of studying battery operation focus on electrochemistry, overlooking this mechanical response, she said.&ldquo;The relationship between the electrochemistry and the development of stress and strain is not well understood,&rdquo; said Sottos. &ldquo;The stress and strain can actually change the way a battery functions, and usually in a negative way &ndash; like the capacity will fade, or it will cause small cracks that cause reactions you don&rsquo;t expect.&rdquo;The researchers combined two techniques to get a more holistic picture of the mechanical forces during battery charging and discharging. They measured the strain, or how much the material expands, by seeding the anode with fluorescent nanoparticles and precisely measuring their movement as the battery went through charging cycles. Meanwhile, they measured stress, or how much the material bends or buckles, using an advanced optical technique.&ldquo;There have been other ways of looking at batteries &ndash; electrochemical methods, circuit methods, techniques involving light &ndash; but no one has done a comprehensive mechanical probe the way that we have,&rdquo; Gewirth said. &ldquo;Stress and strain have been measured separately, but no one has even looked at them together before.&rdquo;The researchers have dubbed their holistic measurement &ldquo;electrochemical stiffness,&rdquo; defined as the ratio of stress to strain.The measurement has already revealed one surprising finding: Right before the lithium is taken up by the anode, there is a spike in stress.&ldquo;We didn&rsquo;t expect there would be a barrier or an impediment to the lithiation process,&rdquo; Gewirth said. &ldquo;First, it shows us where the impediment is for charging. Now that we know where it is, we can work on ways to fix it. Second, it gives us a better idea of how the battery actually works.&rdquo;The electrochemical stiffness measurement technique is not limited to lithium-ion batteries, the researchers say, but can be used on a wide variety of ion-battery materials. Now that they have studied the anode, they are using the technique to study the cathode, which has its own properties and behaviors, Sottos said.&ldquo;These experiments are giving insight that it&rsquo;s not just an electrochemical issue; it&rsquo;s a mechanical issue,&ldquo; Sottos said. &ldquo;We think we are beginning to understand some of the factors that are hindering faster battery charging. We may be able to identify things that let us charge faster and have higher capacity, with less capacity fade over time.&rdquo;The Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, supported this work. Sottos also is affiliated with the&nbsp;<a href="http://beckman.illinois.edu/" target="_blank">Beckman Institute for Advanced Science and Technology</a> at the U. of I.

Illinois professors Nancy Sottos and Andrew Gerwith developed a method to comprehensively measure the mechanical stress and strain in lithium-ion batteries. It revealed a point of stress in charging that, if addressed through new methods or materials, could lead to faster-charging batteries.   Photo by L. Brian Stauffer

fuel cells

Latest Posts

A Robust Fuel Cell that Runs on Methane at Practical Temperatures

Method opens a window on how stress and strain affect battery performance

Profiles