Researchers at the Energy Materials Research Center of the Korea Institute of Science and Technology (KIST) with colleagues at Hyundai R&D have developed a nanocatalyst for high-temperature water electrolysis that can retain a high current density of more than 1A/cm2 for a long time at temperatures above 600 ˚C. An open-access paper on their work is published in Chemical Engineering Journal.
While the degradation mechanisms of nanomaterials at high temperatures have been elusive thus far, the team identified the fundamental reasons of abnormal behavior of nanomateirals and successfully resolved issues, eventually improving performance and stability in realistic water electrolysis cells.
In situ synthesis of perovskite nanocatalysts within the air electrode remarkably improves the performance of high-temperature solid oxide cell. Park et al.
Electrolysis technology can be classified into low- and high-temperature electrolysis. While low-temperature electrolysis operating at temperatures below 100 degrees Celsius has long been developed and is technologically more mature, high-temperature electrolysis operating above 600 degrees Celsius offers higher efficiency and is considered as a next-generation technology with a strong potential for further cost reduction.
However, its commercialization has been hindered by the lack of thermal stability and insufficient lifetime owing to high-temperature degradation, such as corrosion and structural deformation. In particular, nanocatalysts, which are widely used to improve the performance of low-temperature water electrolyzers, quickly deteriorate at high operating temperatures, making it difficult to effectively use them for high-temperature water electrolysis.
To overcome this limitation, the team developed a new nanocatalyst synthetic techniques that suppresses the formation of harmful compounds causing high temperature degradation. By systematically analyzing the nanoscale phenomena using transmission electron microscopy, the researchers identified specific substances causing severe structural alterations, such as strontium carbonate and cobalt oxide and successfully removed them to achieve highly stable nanocatalysts in terms of chemical and physical properties.
When the team applied the nanocatalyst to a high-temperature water electrolysis cell, it more than doubled hydrogen production rate and operated for more than 400 hours at 650 degrees without degradation. This technique was also sucessfully applied to a practical large-area water electrolysis cell, confirming its strong potential for scale-up and commercial use.
Our newly developed nanomaterials achieved both high performance ans stability for high-temperature water electrolysis technology, and it can contribute to lower the production cost of green hydrogen, making it economically competitive with gray hydrogen in the future. For commercialization, we plan to develop automated processing techniques for mass production in cooperation with industry cell manufacturers.—Dr. Kyungjoong Yoon of KIST, corresponding author
Mi Young Park, Jisu Shin, Sun-Young Park, Ji-eun Won, Jun Yeon Hwang, Seungki Hong, Si-Won Kim, Ji-Hoon Jang, Kyung Joong Yoon (2023) “In situ synthesis of extremely small, thermally stable perovskite nanocatalysts for high-temperature electrochemical energy devices,” Chemical Engineering Journal, Volume 476, doi: 10.1016/j.cej.2023.146924