Structural Analysis by Synchrotron XRD of a Ag52Sn48 Nanocomposite Electrode for Advanced Li-Ion Batteries

• Published in: Journal of the Electrochemical Society 2004-01, Vol.151 (10), p.A1738-A1744
• Main Authors: Ronnebro, Ewa, Yin, Jingtian, Kitano, Akiko, Wada, Masahi, Tanase, Shigeo, Sakai, Tetsuo
• Format: Article
• Language: English
• ISSN: 0013-4651
• DOI: 10.1149/1.1793671

The phase transformations of an Ag52Sn48 nanocomposite anode (Ag3Sn + 2Sn) were investigated during electrochemical lithium insertion/extraction. The high performance of the Li-ion battery gives 350 mAh/g for 300 cycles. Electrodes were prepared at selected voltage points in the discharge-charge curves, and high-energy synchrotron X-ray data was collected in order to study the reaction mechanism in detail. Structural analysis with the Rietveld method revealed a sequential Li insertion in the ternary alloy Age 5Li1+xSn between x = 0-1. During discharge Li is inserted into Ag3Sn upon extrusion of Ag to form the ternary compound Ag2LiSn at 0.68 V, and as the voltage decreases the Li content increases, forming the inhomogeneous composition Ag2-xLil+xSn until the end-compound AgLi2Sn forms at 0.15 V. Moreover, below 0.2 V LiySn starts to form; Li7Sn2 and Li22Sn5 were observed. The extruded Ag forms AgLi which further forms Ag5Li8 when more Li is inserted. Finally, at full discharge, AgLi2Sn disintegrates into Li22Sn5 and Ag5Li8.