Enhancing hydrogen storage properties of Ti–Cr–(FeV80) alloys via pre-refining of FeV80 alloy with Y/Zr addition

Abstract

Efficient, safe, and economical hydrogen storage technology is vital for hydrogen’s broad use as an energy carrier, with V-based BCC alloys standing out for their high theoretical storage capacity. However, the high cost of V has restricted their practical application. In this work, a cost-effective Ti–Cr–(FeV80) alloy was successfully synthesized through a pre-refinement process involving the addition of Y/Zr to the FeV80 alloy. The resulting Ti₂₇Cr₂₇(FeV80 + Y)₄₆ alloy exhibited an effective dehydriding capacity of 2.3 wt%, with a capacity retention rate of 97.2% after 200 cycles. Through the analysis of HSC Chemistry 6.0 software and backscattered electron (BSE), it has been discovered that the pre-refinement process significantly reduces the presence of Al, Si, and O impurities, leading to improved compositional uniformity. After the re-refinement, the formation of the Ti–rich phases had been notably curbed. This, along with a marked decrease in the pressure–composition–temperature (PCT) curve’s slope factor from 1.58 to 0.36, results in enhanced hydriding capacity (from 3.2 wt% to 3.7 wt%), reversible dehydriding capacity (from 2.0 wt% to 2.3 wt%), and a remarkable increase in the capacity retention rate (from 75.8% to 97.2%). The kinetics and thermodynamic properties of the alloys were calculated using the Arrhenius and Van’t Hoff equations, providing insights into their performance characteristics. The mechanism behind the alloy’s improved cyclic stability has been elucidated through an analysis of lattice distortion and X-ray photoelectron spectroscopy (XPS). These findings open new routes for the development of cost-effective FeV80-based hydrogen storage materials.

Graphical abstract