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MM: Fachverband Metall- und Materialphysik

MM 17: Hydrogen in Materials: Hydrogen Storage

MM 17.3: Vortrag

Dienstag, 6. September 2022, 14:30–14:45, H46

Microstructural study of MgB₂ in the LiBH₄-MgH₂ composite by TEM — •Ou Jin¹, Yuanyuan Shang², Xiaohui Huang¹, Xiaoke Mu¹, Dorothée Vinga Szabó¹, Thi Thu Le², Stefan Wagner¹, Christian Kübel³, Claudio Pistidda², and Astrid Pundt¹ — ¹Karlsruhe Institute of Technology, Karlsruhe, Germany — ²Helmholtz-Zentrum hereon GmbH, Geesthacht, Germany — ³Technical University of Darmstadt, Darmstadt, Germany

The LiBH₄-MgH₂ composite is known as Reactive Hydride Composite for hydrogen storage that has an exceptional hydrogen storage capacity (up to ∼ 12 wt% H₂) and enhanced thermodynamic properties (down to ∼ 45 kJ/mol H₂). The main challenge that limits the extensive application of this material is its sluggish kinetic performance, which is primarily ascribed to the hampered nucleation of MgB₂ during decomposition. It was found that transition metal-based additives could facilitate the formation of MgB₂ and accelerate the decomposition of LiBH₄-MgH₂. However, the additive effect on the kinetic improvement had not been fully understood until now. To unravel the uncertainties, the formation of MgB₂ in the decomposed LiBH₄-MgH₂ with and without the additive 3TiCl₃-AlCl₃ was studied using manifold transmission electron microscopy techniques. Varied MgB₂ morphologies have been determined, originating from different nucleation centers. Given the heterogeneous nucleation, the crystallographic orientation relationship of the relevant phases is in depth discussed. It turns out that atomic misfit plays a dominant role and directly affects the in-plane strain energy density, leading to varied kinetic performance.