Latest fuel cell material advance overcomes low humidity conductivity problem

September 11, 2006

Fuel cells have been a workable technology for decades – but expensive and lacking in infrastructure. In recent years, researchers have addressed durability, manufacturability, and conductivity challenges in alternative proton exchange membrane (PEM) materials for fuel cells – bringing the hydrogen-based energy source closer to reality.

James McGrath, University Distinguished Professor of Chemistry with the Macromolecules and Interfaces Institute at Virginia Tech, announced his research group's latest development, a PEM material that retains conductivity during low humidity, during his plenary lecture at the Challenges for the Hydrogen Economy symposium during the 232nd National Meeting of the American Chemical Society.

Fuel cells convert chemical energy, usually from hydrogen, to electrical energy. In a PEM fuel cell, the critical exchange takes place through a thin water-swollen copolymer film that contains sulfonic acid (SO3H) groups. Electrons are peeled off by oxidation of the hydrogen atoms and hydrated protons pass through the film to combine with oxygen on the other side to form water as a byproduct.

The efficiency of the exchange process depends upon water, so efficiency – measured as proton conductivity – goes down as humidity goes down. "Up to now, a lot of water has been needed to assist the proton transfer process," said McGrath. "But, in the desert, that is pretty inefficient." McGrath, chemical engineering Professor Don Baird, and their students demonstrated a method for creating a material with improved conductivity even at lower humidity. The U.S. Department of Energy awarded McGrath and Baird's groups $1.5 million over five years to advance the research.

Instead of stirring two kinds of reactive monomers, or small molecules, together to form a new random copolymer, the new material links blocks of two different short polymers in sequences. For example, he would link polymer W (loves water) and polymer d (dry but strong) into a chain this way: WWWWWdddddddWWWWWdddddddd.

The researchers can link a 10- to 50-unit block of a polymer containing acidic groups (SO3H) that like water (hydrophilic) to an equally long block of a polymer that has mechanical strength, thermal stability, and endurance, but hates water (hydrophobic). The chains self-assemble into flexible thin films. Under an atomic force microscope, the film's swirling surface looks like a fingerprint, with light ridges and dark channels. It turns out that the soft hydrophilic polymer forms the dark channels where water is easily absorbed so that the entire film – or proton exchange membrane (PEM) – has an affinity for water transport that is two to three times higher than the present commercially available PEM.

In addition to making PEM materials with better qualities, another goal of the research is to make PEM materials that can be easily manufactured. The self-assembling nature of the block copolymer material into a nanocomposite film is an important attribute. In addition, Baird is working on processing the film from powders using a reverse roll coater, equipment commonly available in the coatings industry but not yet being used to produce PEM material.

Source: Virginia Tech

Explore further: Researchers bring clean energy a step closer

Related Stories

Researchers bring clean energy a step closer

February 27, 2015

For nearly half a century, scientists have been trying to replace precious metal catalysts in fuel cells. Now, for the first time, researchers at Case Western Reserve University have shown that an inexpensive metal-free catalyst ...

Novel electrode boosts green hydrogen research

February 20, 2015

Scientists from the National Physical Laboratory (NPL) have developed a novel reference electrode, and are working with hydrogen energy system manufacturer ITM Power to aid the development of hydrogen production technologies ...

Team advances fuel cell car technology

January 29, 2015

Dr. Yossef Elabd, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, has developed two fuel cell vehicle platforms for both present day enhancements and future innovation.

NREL driving research on hydrogen fuel cells

March 25, 2014

Hydrogen fuel cell electric vehicles (FCEV) were the belles of the ball at recent auto shows in Los Angeles and Tokyo, and researchers at the Energy Department's National Renewable Energy Laboratory (NREL) continue to play ...

Tests prove electrolytic cells are stable at 850 degrees

February 17, 2014

Siemens researchers have demonstrated the long-term stability of ceramic electrolytic cells that are used to produce hydrogen. The results represent a step in the development of new energy storage systems. The use of electricity ...

Recommended for you

'Expansion entropy': A new litmus test for chaos?

July 28, 2015

Can the flap of a butterfly's wings in Brazil set off a tornado in Texas? This intriguing hypothetical scenario, commonly called "the butterfly effect," has come to embody the popular conception of a chaotic system, in which ...

'Carbon sink' detected underneath world's deserts

July 28, 2015

The world's deserts may be storing some of the climate-changing carbon dioxide emitted by human activities, a new study suggests. Massive aquifers underneath deserts could hold more carbon than all the plants on land, according ...

Lobster-Eye imager detects soft X-ray emissions

July 28, 2015

Solar winds are known for powering dangerous space weather events near Earth, which, in turn, endangers space assets. So a large interdisciplinary group of researchers, led by the U.S. National Aeronautics and Space Administration ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.