Preparation of (FeV80)48Ti26+xCr26(x=0–4) alloys by the hydride sintering method and their hydrogen storage performance

Abstract

Abstract The V-Ti-based hydrogen storage alloy (FeV80) 48 Ti 26 Cr 26 was synthesized by the hydride powder sintering method. X-ray diffraction (XRD) analysis results show that the alloy consists of a main BCC phase, a La 2 O 3 phase and a Ti-rich oxide phase. The existence of the Ti-rich oxide phase leads to a loss of Ti element content in the main BCC phase and further results in a lattice contraction. Thus, the hydrogen absorption capacity of the alloy synthesized by the hydride powder sintering method is only 2.8 wt%, with a hydrogen desorption capacity of 1.5 wt%. To address this problem, the effects of Ti element compensation on the microstructure and the hydrogen storage capacities of the alloy were investigated. It was found that the lattice constant of the BCC phase increases and the amount of Ti-rich oxide phase is almost unchanged with increased Ti element compensation, leading to an improved hydrogen storage capacity. When Ti element compensation reaches 4 at%, the hydrogen absorption capacity of the alloy reaches 3.3 wt% with a desorption capacity of 2.0 wt% at room temperature and at a pressure of 10 −4 MPa. The hydrogen desorption plateau slope factor of the (FeV80) 48 Ti 26+x Cr 26 (x = 0–4) alloy prepared by the hydride powder sintering method is as small as that of the alloy prepared by the arc-melting method. Thus the sintering method is a suitable option for the manufacture of V-Ti-based hydrogen storage alloys.