{"72720":{"#nid":"72720","#data":{"type":"news","title":"Chemical Screening Evaluates Fuel Cell Materials","body":[{"value":"\u003Cp\u003EBecause of their efficiency and reduced pollution, fuel cells offer a promising alternative to traditional power sources in transportation and other applications. Yet more durable, less expensive materials are needed before these electrochemical devices replace internal combustion engines in vehicles.\n\u003C\/p\u003E\n\u003Cp\u003EFinding those materials will require analyzing potentially billions of possible material combinations. In response, J. Carson Meredith, an associate professor at Georgia Tech\u0027s School of Chemical and Biomolecular Engineering, is developing a new screening system that will enable researchers to evaluate hundreds or thousands of potential materials in a single experiment. Meredith presented details of this combinatorial toolkit on Sept. 10 at the American Chemical Society\u0027s 232nd national meeting in San Francisco.\n\u003C\/p\u003E\n\u003Cp\u003EWhen it comes to proton exchange membrane (PEM) fuel cells - the type of fuel cell that the automotive industry is focusing on - one of the biggest stumbling blocks is the membrane itself. \n\u003C\/p\u003E\n\u003Cp\u003EResembling a piece of kitchen plastic wrap, the membrane is sandwiched between two electrodes - an anode and cathode - just as in a battery. As hydrogen gas flows into the fuel cell at the anode side, a platinum catalyst separates the hydrogen into electrons and protons. The membrane\u0027s job is to conduct the positively charged protons through to the cathode side and prevent the negatively charged electrons from passing through. Instead, electrons are conducted through an external circuit to the cathode, creating an electrical charge that can power a vehicle\u0027s electrical motor. Then at the cathode side, the electrons reunite with the protons and oxygen to form water as a byproduct.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022Current membranes on the market are costly because they\u0027re made out of fluorinated materials as opposed to conventional hydrocarbon-based plastics,\u0022 Meredith noted. \u0022Durability is another issue. Due to the harsh environment of the fuel cell, the typical lifespan for a PEM is a couple thousand hours. After that, the membranes begin to degrade chemically - and literally fall apart. They develop leaks, and the fuel begins to \u0027cross over\u0027 the oxygen side, causing the electrical current to drop drastically.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003EPart of a multi-partner project funded by the U.S. Department of Energy, Meredith is developing a methodology to produce low-cost, thermally stable membranes. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Our goal is to double the membrane\u0027s durability and cut costs in half,\u0022 Meredith said. In addition to Georgia Tech, project partners include the University of Hawaii and three private companies -- Arkema Inc., United Technologies Corp. and Johnson-Matthey.\n\u003C\/p\u003E\n\u003Cp\u003EIn contrast to traditional membrane development - a synthesis-intensive process that requires many distinct steps - the partners are taking a \u0027formulation approach.\u0027 This involves selecting a number of different polymers, with each one picked for a specific property, and then combining the polymers in one mixing step so the final material retains all of the desired properties.   \n\u003C\/p\u003E\n\u003Cp\u003EOn that wish list of membrane properties are:\n\u003C\/p\u003E\n\u003Cp\u003E* high conductivity for protons with low conductivity for electrons;\u003Cbr \/\u003E\n* a very thin material that still maintains its shape and structural integrity;\u003Cbr \/\u003E\n* the ability to resist acid and hydrolytic degradation; and\u003Cbr \/\u003E\n* the ability to remain hydrated at high temperatures, yet prevent the fuel (hydrogen or methanol) from passing through.  \n\u003C\/p\u003E\n\u003Cp\u003EBesides the unique characteristics of the selected polymers, other factors will affect the final membrane material, such as the ratio of polymers to the mixture, the order of their addition and the speed of stirring.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022Finding the right polymers and parameters is like looking for a needle in a haystack,\u0022 Meredith said, noting there are literally billions of choices. \u0022Formulation is a powerful and under-utilized approach to PEM design, but new tools are necessary to discover how to control the formulations.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EThat\u0027s where combinatorial methods come into play, integrating computational design, sample libraries, high-throughput screening and informatics.\n\u003C\/p\u003E\n\u003Cp\u003EAlthough combinatorial methods have been used in drug discovery, Meredith is pioneering their use in fuel-cell technology and other fields. He has developed a technology for depositing large collections of polymers on a single microscopic slide, using property gradients to create thousands of variations in composition, temperature and thickness.     \n\u003C\/p\u003E\n\u003Cp\u003EThese polymer libraries undergo high-throughput screening, which shows researchers how different samples stack up in terms of mechanical strength, conductivity and water permeability.  \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Combinatorial methods allow us to search through possibilities much more efficiently,\u0022 Meredith said. \u0022We can run through hundreds of materials in just a couple of hours.\u0022\n\u003C\/p\u003E\n\u003Cp\u003EIn contrast to combinatorial methods that Meredith has developed for biomedical applications, the toolkit for fuel-cell membranes requires the capability to screen conductivity and water permeability, and the latter has been one of Meredith\u0027s biggest challenges. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022It sounds simple - expose the material to water vapor and see how much comes through the other side - but it\u0027s subject to a lot of difficulties,\u0022 he explained. \u0022For one thing, it\u0027s hard to get all the water out of these membranes so you can measure what goes in.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003EMeredith has now developed all the basic components for the fuel-cell combinatorial toolkit and is screening known materials to validate them. \n\u003C\/p\u003E\n\u003Cp\u003EHe is quick to note that combinatorial methods are not meant to replace traditional testing where researchers conduct detailed analyses of material. \u0022Our objective is to quickly screen for properties of interest, recognizing that we\u0027re not getting the most accurate measurement possible,\u0022 he explained. \u0022We\u0027re substituting speed for accuracy, which means there is a greater uncertainty.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003EYet there\u0027s a big payoff:  Combinatorial methods help researchers consider - and identify - more promising materials. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022This enables us to look at a much broader range of possibilities,\u0022 Meredith said, explaining that promising polymers can then be analyzed in a more traditional, time-consuming manner. \u0022But if you only use traditional methods, you\u0027re just looking at a few chemistries. These may not be optimal, and you may be overlooking the best material.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: Jane Sanders (404-894-2214); E-mail: (\u003Ca href=\u0022mailto:jsanders@gatech.edu\u0022\u003Ejsanders@gatech.edu\u003C\/a\u003E) or John Toon (404-894-6986); E-mail : (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Contact\u003C\/strong\u003E: Carson Meredith (404-385-2151); E-mail : (\u003Ca href=\u0022mailto:carson.meredith@chbe.gatech.edu\u0022\u003Ecarson.meredith@chbe.gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: T.J. Becker\n\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Combinatorial chemistry may accelerate search for new membrane materials"}],"field_summary":[{"value":"Researchers are developing a new screening system that would allow the simultaneous evaluation of hundreds or thousands of possible material combinations as candidates for future PEM fuel cells.","format":"limited_html"}],"field_summary_sentence":[{"value":"Search techniques may help find fuel cell materials"}],"uid":"27303","created_gmt":"2006-09-10 00:00:00","changed_gmt":"2016-10-08 03:03:29","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2006-09-10T00:00:00-04:00","iso_date":"2006-09-10T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"72721":{"id":"72721","type":"image","title":"Testing candidate fuel cell membranes","body":null,"created":"1449177954","gmt_created":"2015-12-03 21:25:54","changed":"1475894663","gmt_changed":"2016-10-08 02:44:23"},"72722":{"id":"72722","type":"image","title":"Close-up of fuel cell membrane","body":null,"created":"1449177954","gmt_created":"2015-12-03 21:25:54","changed":"1475894663","gmt_changed":"2016-10-08 02:44:23"}},"media_ids":["72721","72722"],"related_links":[{"url":"http:\/\/www.chbe.gatech.edu\/","title":"School of Chemical \u0026 Biomolecular Engineering"},{"url":"http:\/\/www.chbe.gatech.edu\/fac_staff\/faculty\/meredith.php","title":"Carson Meredith"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[],"keywords":[],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}