Studies of the effects of TiCl₃ in LiBH₄/CaH₂/TiCl₃ reversible hydrogen storage system

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• 作者：Dongan Liu^a ; ^b ; Jun Yang^a ; ^{jyang27@ford.com} ; Jun Ni^b ; Andy Drews^a
• 关键词：LiBH4 ; TiCl3 ; Solid-solution ; Molten-solution ; Reversible hydrogen storage
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 出版时间：15 February 2012
• 年：2012
• 卷：514
• 期：Complete
• 页码：103-108
• 全文大小：1139 K

文摘

In the present study, the effects of TiCl₃ on desorption kinetics, absorption/desorption reversibility, and related phase transformation processes in LiBH₄/CaH₂/TiCl₃ hydrogen storage system was studied systematically by varying its concentration (x = 0, 0.05, 0.15 and 0.25). The results show that LiCl forms during ball milling of 6LiBH₄/CaH₂/xTiCl₃ and that as temperature increases, o-LiBH₄ transforms into h-LiBH₄, into which LiCl incorporates, forming solid solution of LiBH₄¡¤LiCl, which melts above 280 ¡ãC. Molten LiBH₄¡¤LiCl is more viscous than molten LiBH₄, preventing the clustering of LiBH₄ and the accompanied agglomeration of CaH₂, and thus preserving the nano-sized phase arrangement formed during ball milling. Above 350 ¡ãC, the molten solution LiBH₄¡¤LiCl further reacts with CaH₂, precipitating LiCl. The main hydrogen desorption reaction is between molten LiBH₄¡¤LiCl and CaH₂ and not between molten LiBH₄ and CaH₂. This alters the hydrogen reaction thermodynamics and lowers the hydrogen desorption temperature. In addition, the solid-liquid nano-sized phase arrangement in the nano-composites improves the hydrogen reaction kinetics. The reversible incorporation/precipitation of LiCl at the hydrogen reaction temperature and during temperature cycling makes the 6LiBH₄/CaH₂/0.25TiCl₃ nano-composite a fully reversible hydrogen storage material. These four states of LiCl in LiBH₄/CaH₂/TiCl₃ system, i.e. ¡°formed-solid solution-molten solution-precipitation? are reported for the first time and the detailed study of this system is beneficial to further improve hydrogen storage property of complex hydrides.