How Crystallite Size Controls the Reaction Path in Nonaqueous Metal Ion Batteries: The Example of Sodium Bismuth Alloying

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• 作者：Jonas Sottmann ; Matthias Herrmann ; Ponniah Vajeeston ; Yang Hu ; Amund Ruud ; Christina Drathen ; Hermann Emerich ; Helmer Fjellvåg ; David S. Wragg
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：28
• 期：8
• 页码：2750-2756
• 全文大小：476K
• 年卷期：0
• ISSN：1520-5002

文摘

Crystallite size effects can influence the performance of battery materials by making the structural chemistry deviate from what is predicted by the equilibrium phase diagram. The implications of this are profound: the properties of many battery materials should be reassessed. Sodium ion battery anodes made from nanocrystalline bismuth form different phases during electrochemical cycling compared to anodes with larger crystallites. This is due to the formation of a metastable cubic polymorph of Na₃Bi on the crystallite surfaces. The structural differences (weaker Na–Bi bonds, different coordination of Na to Bi) between the metastable cubic Na₃Bi phase found in the nanocrystals and the hexagonal equilibrium polymorph which dominates the larger crystallites offer an explanation for the improvements in cycling behavior observed for the nanostructured anode.