KIER Proposes Solution to the "Precipitate Problem" in Seawater Electrolysis

A solution has been proposed to address the persistent "precipitate problem" that arises during seawater electrolysis.

The Korea Institute of Energy Research (KIER) announced on March 13 that the SCI Convergence Research Group, led by Dr. Jihyung Han, has established a direction for advancing seawater electrolysis technology by resolving the issue of precipitate formation, which has previously caused performance degradation and process interruptions.

(From top left clockwise) Ji-hyeok Lim, Intern Student; Kyo-sik Hwang, PhD; Namjo Jeong, PhD; Heesang Ko, PhD; Youncheol Jeong, PhD; Jihyung Han, PhD; Eunjin Jwa, PhD; Jooyoung Lee, Senior Administrative Officer; Minju Kim, Intern. Korea Institute of Energy Technology.

Electrolysis is a technology that produces hydrogen, an eco-friendly energy source, by decomposing water. Recently, research on seawater electrolysis, which utilizes seawater to address freshwater shortages, has been actively conducted.

However, seawater electrolysis has been considered "inefficient" because precipitates caused by magnesium and calcium ions present in seawater accumulate on the electrode surface, reducing performance. Although acid washing or mechanical cleaning can be performed to remove precipitates, the drawback is that continuous hydrogen production is not possible during these cleaning processes.

To overcome this, the research team implemented a new system structure that applies two electrodes for the first time in the world. In this system, hydrogen is produced at one electrode, while at the other electrode, hydrogen production is temporarily stopped to dissolve the precipitates using acidified seawater. By utilizing this principle, both electrodes can switch roles, allowing hydrogen production and precipitate removal to occur simultaneously.

In fact, through experiments, the research team confirmed that by switching the roles of each electrode every 48 hours, the cycle of precipitate formation and complete removal can be repeated.

Notably, after 200 hours of operation, conventional single-electrode seawater electrolysis systems showed an approximately 27% increase in energy consumption due to accumulated precipitates. In contrast, the system developed by the research team exhibited only a 1.8% increase in energy consumption even after more than 400 hours of continuous operation, demonstrating a 15-fold improvement in performance over the single-electrode system.

Additionally, according to the research team, after 400 hours of operation, the hydrogen production catalyst content decreased by 20% compared to the initial level, more than half lower than the content reduction (53%) observed in single-electrode systems, indicating high stability.

Dr. Jihyung Han stated, "This study is a case that proves the precipitate issue, which has long hindered seawater electrolysis technology, can be controlled solely through system design. In particular, it is meaningful as the world’s first proposal of the 'self-healing' concept, where electrodes recover themselves using acidified seawater, thus presenting a new direction for the future development of seawater electrolysis technology."

Meanwhile, this research was conducted jointly with the research team of Professor Joohyun Lim at Kangwon National University, with support from the Convergence Research Group Project of the National Research Council of Science and Technology. The results (paper) were published in the March issue of the international academic journal "Chemical Engineering Journal" in the fields of energy and chemical engineering.

This content was produced with the assistance of AI translation services.