Investigations Of The Li8sn3 Phase In The Binary Li-Sn System Using An Improved Coulometric-Titration Setup

A substantially modified Coulometric Titration setup has been designed and built. In order to validate the new concept's experimental capability, measurements in the well-known Lithium-Tin system are performed at an elevated temperature of 406 degrees C. The second objective of the presented work is to prove the existence of the Li8Sn3 phase. A few researchers have reported the possible existence of this phase equilibrium in the binary system. Yet there are no systematic investigations or clear evidence for existence of this phase. Therefore, we applied the Coulometric Titration using the Galvanostatic Intermittent Titration Technique (GITT) with our new developed experimental setup to the Li-Sn system. Detailed description of the boundary conditions and the measuring method is also given in this work. Our measurements verified an additional intermetallic phase through repetitive cycling around the composition range. In contrast to literature, the phase is found to have a slightly different composition of Li2.635Sn. The measured potential as well as the other known line compounds (e.g. Li13Sn5, Li5Sn2, Li7Sn3) of the Li-Sn system are in very good agreement with the available electrochemical and phase diagram data from literature. (C) 2017 The Electrochemical Society. All rights reserved.