基于CaB6结构产物的LiBH4/金属氢化物复合体系可逆储氢机理研究

LiBH4作为一种高容量轻金属配位氢化物储氢材料备受关注，但较高的吸放氢操作温度和较差的动力学性能阻碍了其实用化进程，并且基于LiBH4的复合储氢材料也难以实现吸放氢温度和动力学性能的同步改善。本项目拟采用热力学和动力学特性研究及准原位物相结构表征的方法，系统研究含有MgH2的LiBH4/CaH2/氢化镧复合体系的可逆储氢机理，探讨多种CaB6结构产物的生成及比例与反应路径的对应关系，揭示CaB6结构产物改善复合材料吸放氢动力学性能的微观机理；通过具有/不具有CaB6结构金属硼化物对应的氢化物替换复合储氢材料中的氢化镧，验证并完善上述作用机理。本项目通过开展LiBH4的热力学和动力学协同改性研究，改善其循环储氢性能，为进一步研究和开发高容量储氢材料提供理论指导意义。

LiBH4, which has the highest hydrogen storage capacity among the light metal complex hydrides, has received much more attentions as a kind of solid-state hydrogen storage material. However, high dehydrogenated temperature and poor kinetics for re-/dehydrogenation prevent it from practical applications, and it is difficult, for LiBH4-based hydrogen storage composites, to achieve the performance improvement simultaneously of the cyclic hydrogen storage properties and re-/dehydrogenated kinetics. Based on the methods of thermodynamic and kinetics researches associate with pseudo-situ structure characterizations, this project intends to implement comprehensive investigations of the reversible hydrogen ab/de-sorption mechanisms to the LiBH4 and multi-metal hydrides complex system, with MgH2 included. The regulation, which relates to the decomposed pathway and the components and structures of metal borides, dehydrogenated from the composite hydride and contained CaB6 structure, is systematically studied. Then, the microscopic mechanism, which improves the de-/hydrogenated kinetics properties by the CaB6 structure products, is also revealed. Finally, the replacement of Lanthanum hydride by several metal hydrides, whose metal borides do or not have CaB6 structure, is employed, in order to verify and ameliorate above mechanism. By this project, the research of synergetic thermodynamic and kinetic destabilization on LiBH4, which promote the cyclic hydrogen storage properties, provide valuable experimental reference to the investigation and development of high-capacity hydrogen storage materials.