A research team led by Professor Gi-Ro Yoon at Konkuk University has developed a next-generation ultra-thin electrolyte membrane technology that significantly improves both performance and durability of hydrogen fuel cells. The breakthrough is expected to accelerate commercialization of hydrogen electric vehicles and strengthen the broader hydrogen economy ecosystem.
The study, conducted in collaboration with the Korea Institute of Industrial Technology (KITECH) and Seoul National University, was published in the January issue of Advanced Energy Materials (Impact Factor 26.0, top 2.5% in JCR ranking) and selected as the Front Cover article.
Hydrogen fuel cells are rapidly expanding beyond passenger vehicles into heavy-duty trucks, buses, trams, ships, and even aircraft. To support these applications, fuel cells must operate stably over extended periods. The electrolyte membrane—also known as the separator—plays a decisive role in determining output, lifespan, and safety. It separates the anode and cathode while selectively allowing proton transport and preventing hydrogen gas crossover.
One of the long-standing challenges in the industry has been thinning the membrane without sacrificing durability. Commercially, reinforced composite membranes supported by porous substrates have been widely adopted to improve mechanical strength. However, conventional ePTFE-based substrates are produced through a top-down stretching and tearing process of pre-formed polymer films, which fundamentally limits precise control over internal pore structures. As membranes become thinner, hydrogen gas permeation increases and mechanical stability decreases, creating a persistent trade-off between thickness and durability.
To overcome these limitations, the research team introduced a novel membrane architecture by combining electrospinning and biaxial stretching. Electrospinning produces nanometer-scale fibers from polymer solutions using electrostatic forces, while biaxial stretching uniformly elongates polymer films or nonwoven mats in two directions at controlled temperatures.
Using electrospinning, the team fabricated a polytetrafluoroethylene (PTFE) nanofiber support characterized by excellent thermal and chemical resistance and low friction. An ionomer—responsible for proton conduction—was densely infiltrated into the nanofiber matrix. The structure was then uniformly stretched in two directions. When the nanofiber nonwoven support was stretched threefold, the overall thickness decreased to approximately one-ninth of its original thickness, while porosity significantly increased.
The resulting reinforced membrane achieved an ultra-thin structure of approximately 19.8 micrometers (µm). Despite being thinner than the commercial benchmark Nafion XL, it demonstrated superior dimensional stability in hydrated conditions, high mechanical strength, and excellent hydrogen gas barrier performance. These characteristics were attributed to fiber interconnection during recrystallization and thermal treatment, combined with uniform ionomer infiltration through expanded pore structures formed during stretching.
Single-cell performance testing confirmed substantial improvements. At 0.6V, the fuel cell incorporating the new membrane achieved a current density of 2.786 A·cm⁻² and a peak power density of 1.986 W·cm⁻², outperforming existing commercial reinforced membranes. In accelerated durability testing involving repeated wet–dry cycling, the membrane maintained stable performance even after more than 21,000 cycles.
Hydrogen crossover current density remained below 3 mA·cm⁻² at 0.4V, satisfying the U.S. Department of Energy (DOE) durability standards for automotive fuel cell membranes. This achievement demonstrates simultaneous realization of ultra-thin structure and high durability—effectively overcoming the traditional trade-off in fuel cell membrane design.
Professor Gi-Ro Yoon of Konkuk University stated that electrospinning allows broad material selection and precise control over nanofiber diameter, density, and structural architecture, and that several Korean companies have already commercialized electrospinning technologies. By integrating stretching and heat-treatment processes into electrospun nanofiber nonwoven supports, membrane thickness and mechanical strength can be flexibly engineered according to application needs.
He emphasized that the study fundamentally resolves the long-standing thickness–durability trade-off in fuel cell membranes and opens pathways for applications beyond hydrogen vehicles, including water electrolysis systems for green hydrogen production.
The research was conducted by Professor Gi-Ro Yoon (Konkuk University), doctoral researchers from KITECH and Seoul National University as co-first authors, along with collaborators from the Korea Research Institute of Chemical Technology, Kyung Hee University, and Hanyang University. The team expects the technology to contribute to domestic technological independence and supply chain stabilization in fuel cell core components, which have traditionally depended on overseas suppliers.
This work was supported by the Ministry of Science and ICT’s Global TOP Strategic Research Initiative, the Ministry of Trade, Industry and Energy’s International Energy Collaboration Program, and the Institute for Basic Science (IBS).
