# Precisely identifies the causes of performance degradation in anion exchange membrane water electrolysis using a two-electrode-based real-time diagnostic technology
# Separates and analyzes individual resistance components during operation, presenting a key platform for accelerating green hydrogen commercialization
CHANGWON, South Korea — Korea Institute of Materials Science (KIMS) , led by President Chul-jin Choi, announced that a research team led by Sung Mook Choi, principal researcher at KIMS, in collaboration with Professor Yangdo Kim of Pusan National University, has developed a two-electrode-based real-time diagnostic technology capable of precisely analyzing the causes of performance degradation in anion exchange membrane water electrolysis (AEMWE) systems under actual operating conditions. This study is significant in that it introduces a new analytical framework that separates and quantifies voltage loss mechanisms within complex water electrolysis systems by individual components.
Water electrolysis is a key technology for hydrogen production through the electrochemical splitting of water. Among its various types, anion exchange membrane water electrolysis (AEMWE) has attracted attention as a next-generation hydrogen production method due to its low cost and efficient hydrogen production. However, performance degradation caused by voltage increases during long-term operation has remained a major challenge, with difficulties in clearly identifying its underlying causes. Conventional electrolysis systems are based on a two-electrode configuration, which allows monitoring of overall performance but makes it difficult to pinpoint specific degradation factors. While previous studies have relied on three-electrode configurations or half-cell experiments to analyze individual electrode reactions, these approaches differ from actual single-cell operating conditions, limiting their applicability to real-world systems.
To overcome these limitations, the research team developed an advanced analytical framework that integrates electrochemical impedance spectroscopy (EIS) data obtained from operating single cells with distribution of relaxation times (DRT) analysis, along with a proprietary method for overpotential separation.
Through this approach, the team successfully quantified voltage loss contributions by categorizing them into charge transfer resistance, hydroxide ion (OH⁻) transport resistance, membrane and contact resistance, and mass transport resistance. The results revealed that voltage increase in water electrolysis systems arises not only from electrode degradation but also from combined effects such as ion transport limitations and mass transfer constraints. The reliability of the analysis was validated through repeated experiments under various electrolyte concentrations and membrane conditions, demonstrating strong reproducibility. The findings are expected to serve as key diagnostic indicators for electrode material development, membrane–electrode assembly design, and optimization of system operation strategies.
Notably, the developed technology enables differentiation of electrode-specific reaction characteristics within practical two-electrode-based systems without requiring additional three-electrode setups. By allowing real-time tracking and analysis of performance degradation during long-term operation, the technology is expected to serve as a commercialization-friendly diagnostic platform, contributing to the design of high-efficiency and high-durability water electrolysis systems.
"This study presents a new analytical framework that enables real-time deconvolution and interpretation of voltage loss mechanisms in complex water electrolysis systems under actual operating conditions," said Sung mook Choi, principal researcher at Korea Institute of Materials Science. "We aim to further develop this technology into a key diagnostic platform that will accelerate the commercialization of green hydrogen production."
This research was supported by the National Research Foundation of Korea under the "H2 NEXT ROUND" program, as well as KIMS's institutional research program and the NRF Nano and Materials Technology Development Program. The findings were published online on March 27, 2026, in the international journal ACS Energy Letters (Impact Factor: 18.9).
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