Probing three-dimensional sodiation–desodiation equilibrium in sodium-ion batteries by in situ hard X-ray nanotomography

• Published in: Nature communications 2015-06, Vol.6 (1), p.7496-7496, Article 7496
• Main Authors: Wang, Jiajun, Eng, Christopher, Chen-Wiegart, Yu-chen Karen, Wang, Jun
• Format: Article
• Language: English
• Subjects: 639/301/299/891; 639/301/930/2735; 639/925; Alloys; Automation; Equilibrium; Humanities and Social Sciences; Lithium; Morphology; multidisciplinary; Science; Science (multidisciplinary); Sodium; Tomography
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms8496

Materials degradation—the main limiting factor for widespread application of alloy anodes in battery systems—was assumed to be worse in sodium alloys than in lithium analogues due to the larger sodium-ion radius. Efforts to relieve this problem are reliant on the understanding of electrochemical and structural degradation. Here we track three-dimensional structural and chemical evolution of tin anodes in sodium-ion batteries with in situ synchrotron hard X-ray nanotomography. We find an unusual (de)sodiation equilibrium during multi-electrochemical cycles. The superior structural reversibility during 10 electrochemical cycles and the significantly different morphological change features from comparable lithium-ion systems suggest untapped potential in sodium-ion batteries. These findings differ from the conventional thought that sodium ions always lead to more severe fractures in the electrode than lithium ions, which could have impact in advancing development of sodium-ion batteries. In situ 3D visualization of sodium-ion battery processes is challenging due to the highly active sodium metal and the sluggish kinetics. Here, the authors present a X-ray tomography technique, which enables tracking the sodiation–desodiation process of a Sn anode in battery operation.