Research progress and development tendency on storage mechanism of multi-principal element alloys for hydrogen/tritium storage

Sustainable clean energy is gradually replacing traditional fossil energy sources in important industrial applications and is placing higher demands on the technologies of energy storage and transportation. The development of multi-principal element alloys (MPEAs) offers a new idea for safe solid-state hydrogen storage materials. Owing to the unique characteristics of complex components and severe lattice distortion, MPEAs are predicted to have better hydrogen storage performance and more probability for modulation and enhancement, allowing them to meet the requirements of different hydrogen storage applications. The unique structure characteristic potentially devotes the improvement of thermodynamic and kinetic performance, such as the hydrogen storage capacity and hydrogen adsorption/desorption properties. Recently, several important modulation factors originating from components and structures facilitate the understanding of the correlation between hydrogen storage properties and microstructure. Here, we highlight the correlations of hydrogen storage mechanism, with the degree of lattice distortion, the element variation or segregation and valence electron concentration. Moreover, the development tendency on the hydrogen storage mechanism based on the advanced microscopy and computational approach is proposed. Especially, the chemically short-range ordered structure in MPEAs is predicted as a potential modification factor of the hydrogen/tritium storage properties.