多元稀土及金属硫化物掺杂快淬-球磨纳米晶/非晶镁基贮氢合金超细颗粒的吸放氢动力学及机理研究

Mg-based hydrogen storage alloy is considered to be a kind of very promising hydrogen fuel carrier of fuel cell owing to its higher hydrogen storage capacity, while their poor hydrogen absorption/desorption kinetics resulting from the extremely high thermodynamics stability of metal hydride limits its practical application. It is confirmed by previous research that although the as-spun Mg2Ni-type hydrogen storage alloy possesses stable nanocrystalline/amorphous structure and fine hydrogen absorption/desorption kinetics property at low temperature, there is still a wide gap reaching the practical demand. In this project, Mg-based alloy containing different rare earth elements with nanocrystalline/amorphous microstructure is first prepared by rapid quenching technology under a vacuum atmosphere, and then we add a small amount of metal sulfides to the above alloy, finally obtaining the ultrafine particle with stable structure by using high-energy ball milling technology. Next, we will investigate the influence of rare earth elements and metal sulfide on the thermodynamics stability as well as hydrogen absorption/desorption kinetics of the nanocrystalline /amorphous Mg-based hydride, explore the relationship between the surface characteristic of the ultrafine particular and hydrogen absorption/desorption kinetics of the alloy, establish the contact among the alloy composition (including the addition amount of metal sulfide and the content of rare earth element), rapid quenching-ball milling technology, the surface characteristics of the ultrafine particle and hydrogen absorption/desorption kinetics property, indicate the mechanism why the ultrafine grains have excellent hydrogen absorption/desorption kinetics and gain the technique parameters of rapid quenching-ball milling technology with which the nanocrystalline/amorphous structure ultrafine particle is stably and efficiently prepared, which provides a reliable experimental basis for ameliorating the hydrogen absorption/ desorption kinetics of Mg-based hydrogen storage materials and has important theoretical significance and helpful value.

镁基贮氢合金因高贮氢量被认为是极具希望的燃料电池氢燃料载体，但其氢化物极高热稳定性导致其吸放氢动力学性能差，阻碍其应用。前期研究证实，快淬Mg2Ni型合金的纳米晶/非晶结构稳定，低温吸放氢动力学性能良好，但距实用化要求尚有较大差距。项目拟采用真空快淬技术制备含有不同稀土元素的纳米晶/非晶镁基贮氢合金，添加微量金属硫化物后用高能球磨制备结构稳定的超细颗粒，研究稀土元素和金属硫化物对纳米晶/非晶镁基贮氢合金氢化物热稳定性及吸放氢动力学的影响；探究超细颗粒的表面特性与其吸放氢动力学之间的关系；建立合金成分(包括金属硫化物掺杂量及稀土元素含量)、快淬-球磨工艺、超细颗粒表面特性与吸放氢性能之间的关系，揭示超细合金颗粒具有良好吸放氢动力学性能的机理，获得稳定高效制备纳米晶/非晶结构超细颗粒的快淬-球磨工艺参数，这为改善镁基贮氢材料吸放氢动力学提供了可靠的实验基础，具有重要的理论意义和重要价值。

Mg基贮氢合金具有理论容量高、可逆性好，储量丰富等一系列优点成为近期贮氢材料研究热点之一，但其较高的吸放氢温度及较差的动力学性能阻碍了其应用。在本项目中，采用真空感应熔炼方法制备了一系列RE–Mg以及RE–Mg–Ni系贮氢合金，并采用真空快淬、机械球磨及添加催化方法制备了具有非晶/纳米晶结构的超细复合材料颗粒，以此来改善上述合金的贮氢特性。研究了合金微观结构、相组成及不同催化剂添加对合金微观结构及吸放氢性能的影响，论述了合金的吸放氢动力学机制，阐明了硫化物对在合金吸放氢过程中的催化机理。本项目研究结果为该类合金的应用和发展提供了理论基础和技术指导。