Investigation of electrochemical and kinetic properties on AB5-type hydrogen storage alloy catalyzed by Yb2O3/C composite

Abstract

To enhance the overall electrochemical properties of AB5-type hydrogen storage alloys, a composite material Yb2O3/C composed of rare earth oxides and carbon-based materials was prepared by an improved blow carbonization method as an additive, and LaNi5 x wt.% Yb2O3/C (x = 0, 2, 4.6, 8) alloy samples were prepared by mechanical ball milling technology. XRD and SEM results show that adding Yb2O3/C composite material can effectively reduce the size of alloy particles and improve ball milling efficiency. Meanwhile, electrochemical kinetic tests showed that the LaNi5- Yb2O3/C alloy has excellent electrochemical performance compared with the undoped alloy, in which LaNi5 + 4 wt% Yb2O3/C exhibits the fastest activation performance and high electrochemical capacity of 292 mAh/g, and has excellent high-fold discharge performance, and the HRD value can reach 72% at a current density of 200 mA/g. However, with the increase of Yb2O3/C content, it will adversely affect the cycle stability of the alloy. This is attributed to the fact that the addition of Yb2O3/C provides the alloy with more catalytic sites and channels for internal hydrogen diffusion while also accelerating alloy pulverization.