Production of AB5 materials from spent Ni-MH batteries with further tests of hydrogen storage suitability

Abstract

A novel approach for the reuse of rare earth (REE) elements generated during hydrometallurgical processing of Ni-MH batteries as alternative sources is provided to valorize Ni-MH batteries wastes. The production of AB5-based alloys from spent Ni-MH waste was thoroughly investigated. The REE elements were recovered as a mixture in oxalate form and annealed at 900 °C to obtain a single-phase REEs oxide REE2O3. Citrate gel and glycine nitrate processes followed by the Ca reduction process under H2 atmosphere were used to produce the AB5 alloys. The alloys were successfully produced, and their crystal structure and morphology have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with supporting energy-dispersive X-ray (EDS) analysis. Nanoparticles with a size of 173±3 nm and 150±8 nm were observed using transmission electron microscopy (TEM) for CG and GNP alloys. Studied samples were subjected to hydrogenation, and the structural changes were depicted.