LiNH2-0.1AlCl3 Self-Propagated Reaction promoted by Ball Milling

FERNÁNDEZ ALBANESI, LUISA; L. PISANO; GARRONI, SEBASTIANO; G. MULAS; F. C. GENNARI

Sassari

Jornada; Sardinia-Chem 2019; 2019

University of Sassari

The LiNH2-LiH (lithium amide-lithium hydride) system is one of the most attractive light-weight materials for hydrogen storage. The mechanical milling process and the addition of AlCl3 (aluminium chloride) improve the re-hydriding and de-hydriding rates, the hydrogen storage capacity and the stability under H2 cycling [1].In further studies, using higher amounts of AlCl3 together with mild thermal treatments in controlled atmosphere, we observed the formation of cubic and hexagonal amide-chloride phases in the Li-Al-N-H-Cl system [2]. It was confirmed that these amide-chloride phases improve H2- storage properties compared to the LiNH2-LiH, providing alternative reaction pathways [3]. The amide-halide phase modifies the hydrogen storage performance of the material. To understand this formation mechanism we focused on the binary system LiNH2-0.1AlCl3. Sample preparation was carried out by ball milling performed in a Spex mill. After 3.3 min of milling, a Self-Propagated Reaction (SPR) starts inside the cell. As a consequence of this short process of mechanical treatment the hexagonal Li-Al-N H-Cl phase was formed. Ammonia gas was detected at this point.Gaseous and solid phases at different milling times were characterized using XRPD, FTIR and DSC with the aim of clarify the formation of Li-Al-N-H-Cl phase from the starting materials and the role of the gases formed immediately before de SPR