2种零维碳材料对Li-Mg-B-H体系储氢性能的影响

Effects of Two Zero-Dimensional Carbon Materials on Hydrogen Storage of Li-Mg-B-H Systems

固态储氢材料中,Li-Mg-B-H体系因放氢路径简单以及具有较高的理论储氢量成为研究的热点,但仍面临着吸放氢反应过程中放氢温度高,放氢动力学性能差等问题。以金属Mg粉作为初始原料,添加2种不同种类的零维碳材料,通过氢化燃烧的方法制备了均匀分散的纳米镁基粒子;进一步采用高能球磨的方法,与LiBH_(4)复合构建复合储氢材料2LiBH_(4)-MgH_(2)@C。研究发现,以上两步法构建的复合储氢材料的储氢性能得到了极大的改善。进一步通过研究吸/放氢动力学、热力学以及循环性能,探索了不同种类的零维碳材料对Li-Mg-B-H体系储氢性能的影响以及作用机制。研究表明,2种零维碳材料的添加不仅为反应粒子提供活性位点,促进储氢粒子的附着、锚定以及成核,同时能够在吸/放氢过程中有效抑制储氢粒子的团聚,进而对复合储氢材料的吸放氢性能起到了积极的促进作用。

Among hydrogen storage materials,Li-Mg-B-H system has attracted a lot of attention due to the simple hydrogen desorption pathway and high theoretical hydrogen storage capacity,but it still faces the disadvantages of high hydrogen desorption temperature and poor hydrogen desorption kinetics.In this study,Mg powder was selected as the initial raw material,and two different zero-dimensional carbon materials were added.Firstly,the Mg-based composite was prepared by hydrogenation,and then the hydrogen storage composite was constructed by ball milling of the as-prepared Mg-based hydrogen storage materials and LiBH_(4).It is found that the above-mentioned two-step method to construct the hydrogen storage composite(2LiBH_(4)-MgH_(2)@C)has greatly improved the hydrogen storage performances.Further studies on the hydrogen adsorption and desorption kinetics,thermodynamics and cycling performances have also been carried out to explore the effects of the added carbon materials.The results show that the addition of carbon materials not only provide active sites for the reaction particles,but also promote the anchoring and nucleation of hydrogen storage particles.Meanwhile,it could effectively inhibit the agglomeration of hydrogen storage particles during the process of hydrogen absorption and desorption,and then play a positive role in promoting the hydrogen absorption and desorption performance of hydrogen storage composite.