In Situ Neutron Powder Diffraction of Li6C60 for Hydrogen Storage

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• 作者：Mattia Gaboardi ; Samuel Duyker ; Chiara Milanese ; Giacomo Magnani ; Vanessa K. Peterson ; Daniele Pontiroli ; Neeraj Sharma ; Mauro Ricc貌
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：19715-19721
• 全文大小：389K
• ISSN：1932-7455

文摘

Li₆C₆₀ is so far the best performing fullerene-based hydrogen-storage material. The mechanism of its reversible hydrogen absorption is not, however, totally known. Here, we report the thermal evolution of Li₆C₆₀ upon deuterium absorption up to 330 掳C and under 60 bar deuterium gas pressure using in situ high-intensity neutron powder diffraction. The temporal resolution of the collected data allowed the hydrogenation of Li₆C₆₀ and the segregation of lithium hydride (here LiD) processes to be distinguished from a mechanistic point of view. During absorption, Li₆C₆₀ undergoes several phase transitions, involving the partial segregation of Li in the form of hydride and the expansion of the face-centered cubic (fcc) lattice, followed by a body-centered cubic (bcc) rearrangement of the deuterated fullerenes. The amount of absorbed deuterium was determined by the analysis of the variation in the scattered neutron intensity and confirmed by an ex situ desorption measurement. This analysis clarifies the complex physicochemical reactions behind the absorption mechanism of this model material and highlights the importance of intercalated lithium in triggering the hydrogenation process.