Challenges and potential future trends on high entropy alloy for solid hydrogen storage: Systematic review

This work consists of a systematic review showing recent progress and trends in the development of high entropy alloys (HEA) for solid-state hydrogen storage. The information was compiled from academic papers from the following databases: Google Scholar, ScienceDirect, Springer, SCOPUS, American Chemical Society, MDPI; as well as the patent banks United States Patent and Trademark Office, Google Patent and lens.org. This article discusses key aspects such as HEA design (elements used, thermodynamic and geometric characteristics, thermodynamic simulations and synthesis methods); HEA evaluation focusing on crystallinity, thermal behavior and hydrogen storage; HEA-related trends including MgH 2 modification, the advancement of lightweight alloys and the use of machine learning. • Systematic review on the development of HEA for hydrogen storage. • Relationship between thermodynamic and geometric parameters on storage capacity. • Role of crystal structure (BCC, FCC, C14 Laves) on hydrogen storage capacity. • Identification of HEA and MEA modified MgH 2 as a current trend in research. • The highest reported storage capacity of 3.7 wt % H 2 falls short of DOE targets.