KIER cracks seawater electrolysis deposit problem with dual electrode system

(Press-News.org) A research team led by Dr. Ji-Hyung Han from the Convergence Research Center of Sector Coupling & Integration at the Korea Institute of Energy Research (President Yi, Chang-Keun, hereinafter “KIER”) has developed a new seawater electrolysis system that overcomes the precipitate formation issue long blamed for performance degradation and process interruptions, while also presenting a new direction for further technology advancement.

Water electrolysis is a technology that produces hydrogen, an eco-friendly energy source, by splitting water. Recently, amid the global freshwater shortage, seawater electrolysis using seawater has been gaining attention as a promising alternative.

However, seawater electrolysis has often been considered inefficient because precipitates formed from magnesium and calcium ions in seawater accumulate on electrode surfaces, leading to performance degradation. It has also been pointed out that continuous hydrogen production is difficult because the deposited precipitates must be removed through acid washing or mechanical cleaning.

To address this issue, KIER researchers developed a new system architecture incorporating two electrodes for the first time in the world. While one electrode produces hydrogen and accumulates precipitates, the other, where precipitates have already built up, temporarily halts hydrogen production and dissolves the deposits using seawater that becomes naturally acidified during operation.

Once the precipitates are completely dissolved, the two electrodes switch roles, enabling hydrogen production and precipitate removal to proceed simultaneously. Through experiments, the researchers confirmed that by simply alternating the roles of the electrodes every 48 hours, precipitate formation and complete removal could be repeated continuously.

In conventional single-electrode seawater electrolysis systems, energy consumption increased by about 27% after 200 hours of operation due to precipitate buildup. By contrast, the system developed by the research team showed only a 1.8% increase in energy consumption even after more than 400 hours of long-term operation, delivering 15 times higher performance than the single-electrode system.

In addition, after 400 hours of operation, the hydrogen evolution catalyst content decreased by only 20% from its initial level, demonstrating superior stability compared with the single-electrode system, which showed a 53% reduction.

Dr. Ji-Hyung Han, the principal researcher of the study, said, “This study demonstrates that the precipitate issue, a major bottleneck in seawater electrolysis, can be controlled solely through system architecture design.” She added, “In particular, by being the first in the world to propose the concept of ‘self-cleaning,’ in which electrodes recover on their own using acidified seawater, this work presents a new direction for future seawater electrolysis technology development.”

Meanwhile, this research was carried out as a collaborative study with Professor Joohyun Lim’s team at Kangwon National University, with support from the Convergence Research Group Project of the National Research Council of Science & Technology (NST). The findings were published in the March issue of Chemical Engineering Journal (IF 13.2), a prestigious international journal in the fields of energy and chemical engineering.

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