Li Yun, Zhang Yuxian, Chen Lixin
School of Mechanical and Electrical Engineering, Quzhou College of Technology, Quzhou, China.
School of Materials Science and Engineering, Zhejiang University, Hangzhou, China.
Front Chem. 2021 May 14;9:693302. doi: 10.3389/fchem.2021.693302. eCollection 2021.
Hydrogen is a potential green alternative to conventional energy carriers such as oil and coal. Compared with the storage of hydrogen in gaseous or liquid phases, the chemical storage of hydrogen in solid complex hydrides is safer and more effective. In this study, the complex hydride composite 2LiBH4-LiAlH with different amounts of TiF was prepared by simple ball-milling and its hydrogen storage properties were investigated. Temperature programmed desorption and differential scanning calorimetry were used to characterize the de/rehydrogenation performance, and X-ray diffraction and scanning electron microscopy (SEM) were used to explore the phase structure and surface topography of the materials. The dehydrogenation temperature decreased by 48°C in 2LiBH4-LiAlH with 15 wt% TiF composites compared to the composite without additives while the reaction kinetics was accelerated by 20%. In addition, the influence of hydrogen back pressure on the 2LiBH4-LiAlH with 5 wt% TiF composite was also investigated. The results show that hydrogen back pressure between 2.5 and 3.5 bar can improve the reversible performance of the composite to some extent. With a back pressure of 3.5 bar, the second dehydrogenation capacity increased to 4.6 wt% from the 3.3 wt% in the 2LiBH-LiAlH composite without hydrogen back pressure. However, the dehydrogenation kinetics was hindered. About 150 h, which is 100 times the time required without back pressure, was needed to release 8.7 wt% of hydrogen at 3.5 bar hydrogen back pressure. The SEM results show that aluminum was aggregated after the second cycle of dehydrogenation at the hydrogen back pressure of 3 bar, resulting in the partial reversibility of the 5 wt% TiF-added 2LiBH4-Li3AlH composite.
氢是一种潜在的绿色能源，可替代石油和煤炭等传统能源载体。与氢气的气相或液相储存相比，在固体复合氢化物中进行氢气的化学储存更安全、更有效。在本研究中，通过简单的球磨制备了具有不同TiF含量的复合氢化物复合材料2LiBH4-LiAlH，并对其储氢性能进行了研究。采用程序升温脱附和差示扫描量热法表征脱氢/加氢性能，采用X射线衍射和扫描电子显微镜（SEM）探索材料的相结构和表面形貌。与无添加剂的复合材料相比，含15 wt% TiF的2LiBH4-LiAlH复合材料的脱氢温度降低了48°C，同时反应动力学加快了20%。此外，还研究了氢气背压对含5 wt% TiF的2LiBH4-LiAlH复合材料的影响。结果表明，2.5至3.5 bar的氢气背压可在一定程度上提高复合材料的可逆性能。在3.5 bar的背压下，第二次脱氢容量从无氢气背压的2LiBH-LiAlH复合材料中的3.3 wt%增加到4.6 wt%。然而脱氢动力学受到阻碍。在3.5 bar氢气背压下释放8.7 wt%的氢气需要约150 h，这是无背压时所需时间的100倍。SEM结果表明，在3 bar氢气背压下进行第二次脱氢循环后，铝发生了聚集，导致添加5 wt% TiF的2LiBH4-Li3AlH复合材料出现部分可逆性。
