Characterization of the LaNi(5-x)Sn(x) - H system

E.M. BORZONE; A. BARUJ; M.V. BLANCO; G. O. MEYER

Florianópolis

Congreso; XI Encontro da SBPMat 2012; 2012

Sociedade Brasileira de Pesquisa em Materiais

Metal hydrides are used in a broad range of applications including hydrogen storage, thermal compression, gas separation and batteries. Each specific application makes use of the reversible hydriding - dehydriding reaction M+(0.5)x H2 ↔ MHx + heat and its performance depends on the detailed properties of this reaction. Relevant characteristics of the system include hydrogen absorption capacity, relation between absorption/desorption pressure and temperature, plateau slope, hysteresis, cycling stability, ease of activation and reaction kinetics. For LaNi5 and related AB5 alloys, many of these properties can be tailored by partial substitution of the constituents in order to optimize the process. In this work we present a study on the LaNi5-xSnx system and its hydriding - dehydriding properties for 0 ≤ x ≤ 0.5 in the 300 - 380 K temperature range. Sn substitution is found to lower the equilibrium pressure and accelerate the reaction kinetics. A small loss in hydrogen capacity is measured in the substituted alloys. Hysteresis loss decreases with x. All samples present good resistance to absorption/desorption cycling. The results for the studied system make it a strong candidate for low-pressure stationary applications such as hydrogen separation, purification and first stage of thermal compression.