在金属氢化物储氢领域，Mg2NiH4因具有较高的储氢容量和较快的吸放氢动力学，以及独特的结构和电子特性而倍受青睐。Mg2Ni氢化产物晶型结构的多样性以及其间复杂的相变过程使得多晶型多维度Mg2NiH4的可控制备、结构分析以及储氢性能研究变得更具挑战性，且关于不同低温相的形成机制及其对储氢性能的影响仍然不清楚。本项目提出特定气-固合成技术制备具有不同相组成和微观形貌的镁镍合金氢化物体系，实现多晶型多维度纳米Mg2NiH4的可控制备。深入解析Mg2NiH4同质异构体的微观结构特征及相转变机制，通过对合成工艺与产物相结构、微观形貌以及储氢性能的系统研究，揭示不同低温相的形成机制，以及材料相结构特别是高密度层错和孪晶对储氢性能的影响规律，提出材料结构与储氢性能的关联机制，阐明多晶型多维度纳米Mg2NiH4储氢性能的形貌依赖特性及反应机理，为金属氢化物储氢性能的改善提供理论和实践支撑。

Mg2NiH4 has been widely studied as advance metal hydride owing to its relatively high hydrogen storage capacity, fast hydriding/dehydriding kinetics, peculiar structure and electronic property. However, the diversity in crystal structure and complexity in phase transformation of Mg2NiH4 pose a challenge to the study of polymorphic and multidimensional Mg2NiH4, regarding its controllable preparation, structural analysis and hydrogen storage properties. Moreover, the formation mechanism of different low-temperature (LT) phases and its effect on the hydrogen storage properties are still unclear. In this project, we propose a novel gas-solid-based methodology to prepare Mg2NiH4 with different phase structures and microstructures, and realize the controllable preparation of polymorphic and multidimensional nano-Mg2NiH4. The microstructure and phase transformation mechanism of Mg2NiH4 isomers will get in-depth analysis. The preparation technique, phase structure, microstructure and hydrogen storage properties of Mg2NiH4 will be studied systematically. We aim to reveal the formation mechanism of different LT phases, and the effect of phase structure, in particular high-density stacking faults and twin crystals, on hydrogen storage properties. We will also discover the relation mechanism between material structures and hydrogen storage properties, and demonstrate the morphology-dependent characteristics of hydrogen storage properties and reaction mechanism of polymorphic and multidimensional nano-Mg2NiH4. This study will lay theoretical and practical foundation for the improvement of hydrogen storage properties of metal hydrides.