Enhanced reversible hydrogen storage performance of NbCl₅ doped 2LiH-MgB₂ composite

详细信息    查看全文

• 作者：Xuezhang Xiao ; Shunkui Wang ; Guoping Tu ; Liuting Zhang ; Xiulin Fan ; Shouquan Li ; Hongwei Ge ; Qidong Wang ; Lixin Chen
• 关键词：Hydrogen storage ; LiH&ndash ; MgB2 ; NbCl5 ; Reversibility ; Kinetics
• 刊名：International Journal of Hydrogen Energy
• 出版年：4 February, 2014
• 年：2014
• 卷：39
• 期：5
• 页码：2132-2141
• 全文大小：2090 K

文摘

2LiBH₄聽+聽MgH₂ system is considered as an attractive candidate for reversible hydrogen storage with high capacity and favorable thermodynamics. However, its reaction kinetics has to be further improved for the practical application. In this work, we investigated the effect of NbCl₅ additive on the de/hydrogenation kinetics and microstructure refinement in 2LiH-MgB₂ composite systematically. The hydrogenation and dehydrogenation kinetics of 2LiH-MgB₂ composite can be significantly enhanced with the increase of NbCl₅ content. The 3聽mol% NbCl₅ doped 2LiH-MgB₂ composite exhibits the superior reversible hydrogen storage performance, which requires 50聽min to uptake 9.0聽wt% H₂ at 350聽掳C and release 8.5聽wt% H₂ at 400聽掳C, respectively. In contrast, the undoped 2LiH-MgB₂ sample uptakes 6.2聽wt% H₂ and releases 3.1聽wt% H₂ under identical measurement conditions. Moreover, the 3聽mol% NbCl₅ doped 2LiH-MgB₂ composite can release more than 9.0聽wt% H₂ within 300聽min at 400聽掳C without obvious degradation of capacity over the first 10 cycles. Microstructure analyses clearly indicate that NbCl₅ additive first reacts with LiH to form Nb and LiCl during ball-milling process, and then NbH is formed after the first hydrogenation and stabilized upon further de/hydrogenation cycling. The well-distributed NbH active species play an important role in the improvement of de/hydrogenation kinetics for Li-Mg-B-H system through facilitating hydrogen diffusion rapidly as well as prevent the particles from further growth in the subsequent hydrogenation and dehydrogenation processes.