Metal Hydrides for Hydrogen Storage: Overview and Performance Evaluation Methods

Hydrogen is being widely explored as a promising alternative to fossil fuels due to its numerous advantages,such as its abundance on Earth, high energy density, and low environmental impact upon combustion. In particular,solid-state hydrogen storage systems have attracted significant attention because of their potential for loweroperating pressures and higher volumetric energy densities. Nevertheless, the practical utilization of metal hydridesfor hydrogen storage faces major challenges due to thermodynamic and kinetic limitations, which hinder theirwidespread adoption. Here, we introduce metal hydrides as hydrogen storage materials, classifying them byhydrogen bonding modes, formation pathways, and thermodynamic characteristics. Furthermore, we outlineperformance evaluation methods―including pressure–composition–temperature analysis, kinetic modeling, andcycling stability―and discuss how to interpret the resulting metrics.