Modification of lithium borohydride and magnesium hydride mixture for hydrogen storage

Abstract

In this work, LiBH4 was mixed with magnesium hydride (MgH2) in a 2:1 molar ratio (mixture) in order to investigate the hydrogen desorption/absorption properties. In the first part, the mixture milled for 1 h was observed for its hydrogen desorption/absorption mechanism. The results showed that, when the temperature was lower than 400°C, the released hydrogen was from the partial decomposition of LiBH4 and MgH2. At 450°C, there was the formation of MgB2 and LiH. 3 mol% of TiCl3, HfCl4, and ZrCl4 was also added into the mixture. It was found that all the catalyzed mixtures had lower desorption temperatures. The effects of ball-milling time on the hydrogen desorption/absorption behaviors of the mixture were studied in the second part. It was found that the increase in the ball-milling time resulted in the decrease in the desorbed temperature as well as the hydrogen capacity. In the third part, Ti, TiO2, and TiCl3 were added into the mixture and milled for 5 h. The results showed that doping with Ti resulted in the highest amount of hydrogen, 5.0 wt.%, released from the mixture. In the fourth part, the effects of initial pressure on the hydrogen storage properties of the mixture milled for 5 h were investigated. The results exhibited that the mixture decomposing under 0.15 MPa hydrogen had the highest reversible hydrogen capacity of 5.0 wt.%.