Improving the Hydrogen Storage Property of Sm<sub>6.5</sub>Mg<sub>93.5</sub>-TiMn<sub>2</sub> by Accelerating H<sub>2</sub> Dissociation/Recombination and H Diffusion
Zhuohan Zhang, Ying Cheng, Zhichao Yu, Wenfeng Wang, Yuan Li, Zhaoyang Liu, Shumin Han
Abstract
The development and preparation of composites with multiple active sites and multiple catalytic processes are of great significance for improving the hydrogen storage property of the Mg/MgH 2 system. Herein, a TiMn 2 -type Ti 0.90 Zr 0.10 Mn 1.30 Cr 0.40 V 0.30 hydrogen storage alloy and Sm 6.5 Mg 93.5 - x wt % Ti 0.90 Zr 0.10 Mn 1.30 Cr 0.40 V 0.30 ( x = 0, 5, 10, and 30) composites were successfully prepared. The TiMn 2 hydrogen storage alloy was stable throughout the hydrogen storage performance test. Owing to alloying and hydrogenation-ball-milling, in situ generated Sm 3 H 7 possessed abundant active sites for accelerating H diffusion, and the uniformly distributed TiMn 2 hydrogen storage alloy promoted H 2 dissociation/recombination in Sm 6.5 Mg 93.5 -10 wt % TiMn 2 composite. The Sm 6.5 Mg 93.5 -10 wt % TiMn 2 composite absorbed 4.04 wt % H 2 within 3600 s at 373 K and desorbed 4.41 wt % H 2 within 500 s at 623 K. The Sm 6.5 Mg 93.5 -10 wt % TiMn 2 composite exhibited excellent cycling stability with 97.0% retention of hydrogen absorption after 50 hydrogen absorption and desorption cycles. Microstructural analysis showed that Sm 3 H 7 and TiMn 2 catalytically active substances were dispersed in the Mg/MgH 2 system. The uniformly dispersed Sm 3 H 7 and TiMn 2 catalyst afforded the Sm 6.5 Mg 93.5 -10 wt % TiMn 2 composite with excellent kinetic properties.