High-Entropy Hydrides for Fast and Reversible Hydrogen Storage at Room Temperature: Binding-Energy Engineering via First-Principles Calculations and Experiments

TL;DR

This study combines first-principles calculations and experiments to design high-entropy alloys capable of fast, reversible hydrogen storage at room temperature with high stability and capacity, advancing solid-state hydrogen storage technology.

Contribution

It introduces a novel approach using theoretical and experimental methods to develop high-entropy hydrides with optimized binding energies for efficient hydrogen storage.

Findings

Reversible hydrogen storage in HEAs at room temperature

Hydrogenation occurs without activation or catalytic treatment

Storage capacity exceeds that of commercial LaNi5

Abstract

Despite high interest in compact and safe storage of hydrogen in the solid-state hydride form, the design of alloys that can reversibly and quickly store hydrogen at room temperature under pressures close to atmospheric pressure is a long-lasting challenge. In this study, first-principles calculations are combined with experiments to develop high-entropy alloys (HEAs) for room-temperature hydrogen storage. TixZr2-xCrMnFeNi (x = 0.4-1.6) alloys with the Laves phase structure and low hydrogen binding energies of -0.1 to -0.15 eV are designed and synthesized. The HEAs reversibly store hydrogen in the form of Laves phase hydrides at room temperature, while (de)hydrogenation pressure systematically reduces with increasing the zirconium fraction in good agreement with the binding energy calculations. The kinetics of hydrogenation are fast, the hydrogenation occurs without any activation or catalytic treatment, the hydrogen storage performance remains stable for at least 1000 cycles, and the storage capacity is higher than that for commercial LaNi5. The current findings demonstrate that a combination of theoretical calculations and experiments is a promising pathway to design new high-entropy hydrides with high performance for hydrogen storage.