亚晶格结构对超堆垛储氢合金电化学性能的影响及机制研究

Superlattice hydrogen storage alloys are getting increasing attention as a novel negative electrode material for nickel-metal hydride batteries. However these alloys have complex stacking structures, which makes it hard to grasp the relationship between structure and properties, limiting further improvement in their electrochemical properties. This project is proposed to explore the relationship between the alloy’s structure and their electrochemical properties by studying the microstructure changes of sublattices which are the basic units of the super-stacking structures. Based on the previously obtained single-phase AB3-, A2B7- and A5B19-type La-Mg-Ni-based super-stacking alloys, the sublattice structure characteristics including lattice constants, cell parameters, matching degree between neighboring sublattices, anisotropic, etc. will be studied. Meanwhile, by partial elemental substitution, the effects of atomic radius, element electronegativity, atomic local structure, etc. on the sublattice structure will be investigated. Through real-time data acquisition and tandem analysis, the dynamic changes in expansion/contraction sequence, matching degree as well as the atomic occupation and local structure of the sublattices during charge/discharge will be studied, thereby to explore the difference in the hydrogen absorption/desorption behavior of the sublattices with different stacking modes and the effects of substitutional elements on the sublattice structural stability. In combination with electrochemical results, the effects and affecting mechanism of sublattice structure on the electrochemical properties will be revealed, which offers theoretical guidance for designing and preparing novel high-performance hydrogen storage alloys.

超堆垛储氢合金作为镍氢电池新型负极材料，日益受到关注。但这类合金具有复杂的堆垛结构，结构与性能的关系难以把握，限制了其电化学性能的进一步改善。本项目拟通过研究堆垛结构基本单元亚晶格的微观结构变化，深入考察合金结构与电化学性能的关系。基于前期已获得的单相AB3型、A2B7型和A5B19型La-Mg-Ni系超堆垛合金，研究不同堆垛模式亚晶格的晶格参数、晶胞体积、相邻亚晶格匹配性和各向异性等结构特征，并通过元素取代，探讨原子半径、元素电负性以及原子局域结构等对亚晶格结构的影响。通过实时数据采集和串联分析，深入考察充/放电过程中亚晶格膨胀/收缩顺序、匹配程度以及原子占位和局域结构等的动态变化过程，探讨不同堆垛模式亚晶格的吸/放氢行为差异和元素组成对亚晶格结构稳定性的影响。结合合金电化学性能测试结果，揭示亚晶格结构对合金电化学性能的影响规律及机制，为设计制备高性能储氢合金电极材料提供理论指导。

超堆垛储氢合金作为镍氢电池新型负极材料，日益受到关注。但这类合金具有复杂的堆垛结构，结构与性能的关系难以把握，限制了其电化学性能的进一步改善。本项目研究了堆垛结构基本单元亚晶格的微观结构变化，深入考察了合金结构与电化学性能的关系。基于前期已获得的单相A2B7型La-Mg-Ni系超堆垛合金，研究了其超晶格堆垛模式，并通过Pr、Nd、Gd等不同含量的稀土元素取代La，探讨了原子半径、元素电负性等对亚晶格结构的影响，通过实时数据采集和串联分析，深入考察了充/放电过程中亚晶格膨胀/收缩顺序和匹配程度的动态变化过程，探讨了元素组成对亚晶格结构稳定性的影响及其与合金的电化学及储氢性能的联系。此外，将具有[AB5]亚晶格的组成制备成AB5型单相合金，对其长期吸放氢性能和A侧及B侧元素对其结构和和吸放氢性能的影响进行了研究；且在以上研究的基础上，通过调节合金的相组成和相结构，进一步优化了La-Mg-Ni系超堆垛储氢合金的电化学性能，为设计制备高性能储氢合金电极材料提供了理论指导。