Enhancing Hydrogen Storage in TiVCrMn-Based BCC Alloys: A Comparative Study of Co, Ni, and Fe Modifications

Abstract

Advanced hydrogen storage materials are essential for the development of safe and efficient hydrogen energy systems. Within the spectrum of potential candidates, the significant interest in V-Ti-Cr-Mn-based BCC solid solution alloys stems from their ability to offer both a high theoretical hydrogen storage density and kinetically favorable reactions. However, the stability of the monohydride phase (VH) in pure vanadium and some V-based alloys often leads to low reversible hydrogen storage capacities. This study investigates the effect of partially substituting Mn with Co, Ni, and Fe on the structural, thermodynamic, and kinetic properties of TiV1.2Cr0.8Mn0.3 BCC solid solution alloys. To investigate the effects of elemental substitution, four alloys—TiV1.2Cr0.8Mn0.3, TiV1.2Cr0.8Mn0.15Co0.15, TiV1.2Cr0.8Mn0.15Ni0.15, and TiV1.2Cr0.8Mn0.15Fe0.15—were prepared via arc-melting. XRD analysis indicated that all samples maintained a single BCC phase. Furthermore, the observed systematic peak shift corresponded to variations in lattice constants, which is a consequence of the distinct metallic radii of the substituting elements. SEM-EDS mapping confirmed homogeneous elemental distributions in all alloys. The substitution of Mn with Co, Ni, and Fe regulated the hydrogen absorption capacity and plateau pressure. Specifically, the Fe-substituted alloy showed a favorable balance among capacity, plateau pressure, sorption kinetics, and cycling stability. The research offers critical insights into tailoring the hydrogen storage characteristics of TiVCrMn-based alloys via elemental substitution, providing a pathway to high-performance materials for storing hydrogen.