Department of Energy Systems Research

Development process of various hydrogen storage media toward clean green energy 

An international research team including Professor Byungmin Ahn of Ajou University has published a comprehensive review paper on solid-state hydrogen storage technologies using high-entropy alloys (HEAs).

The paper, titled “A comprehensive review of the prospects for future hydrogen storage in materials—Application and outstanding issues,” was published online on July 18 in the International Journal of Energy Research (Impact Factor: 5.164, top 1.47% in JCR ranking). The journal is the top-ranked publication in the field of nuclear science and technology.

The study’s first author is Dr. Sheetal Kumar Dewangan, a postdoctoral researcher at Ajou University’s Institute of Engineering Research. Professor Byungmin Ahn (Department of Materials Science and Engineering / Department of Energy Systems Research in Graduate School) and Professor Ashutosh Sharma (Department of Materials Science and Engineering) served as co-corresponding authors, while Professor Man Mohan of the Lungta Institute of Engineering and Technology (India) and Professor Vinod Kumar of the Indian Institute of Technology Indore participated as co-authors.

In this review, the research team compared hydrogen storage mechanisms using high-entropy alloys with those of conventional metal hydride-based storage systems, presenting the latest research trends and future outlook in the field.

Hydrogen is regarded as one of the most promising energy sources for achieving carbon neutrality, and research on safe and efficient hydrogen storage technologies is actively progressing. Currently, compressed gas storage is the most common method, but it has low storage efficiency and high explosion risk, making transportation and long-term storage challenging. Cryogenic liquid hydrogen storage offers higher efficiency but requires high energy consumption and is unsuitable for long-term use.

In contrast, solid-state hydrogen storage, which stores hydrogen by forming bonds within metal alloys, provides high storage efficiency and enhanced safety, enabling long-term hydrogen retention without explosion risks. As a result, solid-state storage is gaining considerable attention worldwide.

Among solid-state storage materials, high-entropy alloys (HEAs) — alloys composed of multiple metallic elements in nearly equal proportions without a single dominant element — have recently emerged as a new paradigm in metallic materials research. These alloys are known for their superior functional properties and extreme environmental resistance, making them suitable for cryogenic, heat-resistant, and nuclear materials applications.

HEAs typically consist of five or more metal elements with different atomic radii, leading to a variety of interstitial lattice sites within the crystal structure. These diverse lattice sites allow for greater hydrogen absorption, enhancing storage capacity compared to traditional hydrogen storage alloys. The research team analyzed and compared recently developed HEA compositions for hydrogen storage and discussed future directions for research and development.

Professor Ahn explained,

“Our ongoing research aims not only to improve hydrogen storage efficiency through high-entropy alloys but also to develop HEA-based solid hydrogen storage materials free from rare-earth elements, which are increasingly being weaponized as strategic resources.”

This research was supported by the National Research Foundation of Korea (NRF) through the Mid-Career Researcher Program and the Basic Research Laboratory Program.

Mechanism of hydrogen storage and release through chemical absorption/desorption within metal crystal lattices