Improved hydrogen storage capacity and cyclic properties of TiCr(FeV80) alloys by heat treatment and Ce doping

Abstract

V-based BCC solid solution alloys stand out for their exceptional hydrogen storage capacity at room temperature, yet they encounter obstacles in reversibility, cost-efficiency, and stability, hindering their widespread applications. In this work, a low-cost and high-performance Ti₃₁Cr₃₅(FeV80)₃₄ alloy was prepared by heat treatment and Ce doping with an effective dehydriding capacity of 2.28 wt% and a capacity retention rate of 93.2% after 300 cycles. Analysis using XRD and SEM reveals that heat treatment significantly reduces the accumulation of the C14 Laves phase, while Ce doping mitigates the accumulation of Ti-rich phases, thereby enhancing the compositional uniformity of the alloy. Notably, after heat treatment and Ce doping, the slope factor in the PCT curve has dropped significantly from 1.58 to 0.36, leading to an increase in reversible hydrogen storage capacity from 2.03 to 2.28 wt%. Furthermore, the dehydriding enthalpy value of the Ti₃₁Cr₃₅(FeV80)₃₄ alloy has decreased from 39.16 to 37.91 kJ/mol. Remarkably, the cycling performance of the alloy, following 1 wt% Ce doping, exhibits excellent stability. This stability is primarily attributed to the enhancement of the alloy's powdering resistance through Ce doping, which also preserves the metallic state content of Ti, Cr, and V during the cycling process. This advancement holds significant promise for the development of cost-effective and reliable hydrogen storage alloys.