Fuel cells, which offer a cleaner, more efficient alternative to the combustion of gasoline and other fossil fuels, are an important enabling technology for the nation’s energy portfolio.

“Hydrogen-powered polymer electrolyte membrane fuel cells have already demonstrated the potential to replace internal-combustion engines in vehicles and to provide power in stationary and portable applications,” says Ajay Prasad, director of the Center for Fuel Cell Research at the University of Delaware.

Fuel cells are energy efficient and clean, and the hydrogen fuel can be generated from a variety of domestic sources. However, a major challenge to commercialization of this technology is the durability of the membrane, which is typically made from a polymer called Nafion^®. During fuel cell operation, the membrane undergoes chemical and mechanical degradation, leading to cracks and pinholes that shorten its life.

To address this issue, Prasad and two colleagues from the UD Department of Mechanical Engineering, Liang Wang and Suresh Advani, have developed a self-healing membrane incorporating microcapsules prefilled with a Nafion^® solution. The work is reported in a paper published in the Journal of The Electrochemical Society. A patent application has also been filed.

“The microcapsules are designed to rupture when they encounter defects in the membrane and then release the prefilled Nafion^® solution to heal the defects in place,” Wang explains.

Durability testing of the developed membrane has confirmed that the self-healing functionality could greatly extend its useful life.

“Membrane defects are impossible to detect and repair in an operating fuel cell,” Advani says. “The only solution currently is to replace the entire membrane electrode assembly, which is prohibitively expensive.”

“The possibility of employing self-healing polymeric materials that can heal cracks and pinholes in place is an exciting prospect for extending the working life and safety of such systems while also reducing the life-cycle cost,” he adds.

About the research

The paper appeared in the Journal of The Electrochemical Society on Sept. 3, 2016.

The research was supported by the University of Delaware’s Fuel Cell Bus Program, which is funded by the Federal Transit Administration.

Liang Wang is an associate scientist in the Department of Mechanical Engineering.

Suresh Advani is George W. Laird Professor and chair of the Department of Mechanical Engineering.

Ajay Prasad is Engineering Alumni Distinguished Professor in the Department of Mechanical Engineering and director of the Center for Fuel Cell Research.