Scientists have developed a fatigue-resistant electrolyte membrane with an interpenetrating polymer network that is reported to prolong the lifespan of a fuel cell.

GWANGJU, South Korea—A novel approach to address environmental challenges is the development and commercialization of robust hydrogen fuel cells. These cells contain a polymer electrolyte membrane that serves as a barrier between the electrodes (the conductors that enable the flow of electricity through a substance). This membrane conducts protons but inhibits the movement of electrons, hydrogen molecules, and oxygen molecules, according to a release from Incheon National University (INU), South Korea.

When a vehicle speeds up or slows down, the fuel cell operates inconsistently, leading to varying water production and causing the membrane to expand and contract. The repetitive deformation over time results in the formation of cracks, accelerating the undesired transport of hydrogen through the membrane and ultimately causing operational failure.

Some methods employed to address these cracks include radical scavengers and hydrocarbon electrolyte membranes. However, although these approaches offer some defense, they are not capable of entirely preventing the formation and propagation of these cracks, according to the release.

In a recent study led by Associate Professor Sang Moon Kim, Ph.D., from Incheon National University and Professor Zhigang Suo from Harvard University, a team of researchers developed a polymer electrolyte membrane that is resistant to fatigue. The study was published in the journal Advanced Materials on December 31, 2023.

”To ensure the long-term stable operation of fuel cells, it is essential to develop an electrolyte membrane with high resistance to repetitive fatigue failure that reflects the actual operating environment and degradation process of fuel cells,” Kim said in the release. “In our study, we utilized an interpenetrating network to intentionally distribute repetitive stress.”

In this study, the researchers created a category of fatigue-resistant electrolyte membranes, consisting of an interpenetrating network of Nafion and perfluoropolyether (PFPE). Nafion is a commonly used plastic electrolyte with proton-conducting properties, while PFPE creates a durable, rubbery polymer network. The incorporation of the rubber slightly diminishes electrochemical performance but markedly enhances fatigue threshold and lifespan, the release said.

The membranes produced had varying levels of PFPE. Among them, the one with 50 percent saturation was reported to have exhibited reasonable electrochemical performance. In comparison to the original Nafion, this Nafion-PFPE membrane reportedly elevates the fatigue threshold by 175 percent and extends the lifespan of the fuel cell by 1.7 times.

Additionally, the unmodified Nafion membrane exhibits a lifespan of 242 hours, whereas the composite membrane was observed to have a lifespan of 410 hours. These results collectively suggest that incorporating the rubbery network modestly reduces electrochemical performance but significantly improves fatigue resistance and overall lifespan, according to the release.

The study is said to hold considerable significance across diverse applications. The introduction of a fuel cell system with stability, durability, and performance has the potential to pave the way for innovations in various industries. Beyond the realm of fuel cell vehicles, it can impact the development of advanced technologies in drones, personal air vehicles, backup power sources, forklifts, bicycles, scooters, and more.

“Furthermore, the strategy for enhancing fatigue resistance can be extended and applied to ion filters, battery separators, and actuation systems,” said Kim. “This allows for broad application in high-durability, long-life desalination filters, flow battery separators, lithium metal battery separators, and artificial muscles.”

Overall, this work is said to make a valuable contribution to the advancement of long-lasting energy conversion and storage systems.

The title of the original paper is “Fatigue-resistant Polymer Electrolyte Membranes for Fuel Cells.”