Compton Scattering Imaging for Operando Observation of Lithiation State on Commercial Lithium Battery Cells

Abstract

X-ray Compton scattering imaging technique based on synchrotron radiation is a unique technique to observe lithiation sate in the electrode of commercial lithium battery cells under operando and in-situ conditions. The advantage of this technique is using high-energy which over 100 keV X-rays as an incident beam. High-energy X-rays allow to nondestructively observe the electrochemical reaction in the cells because high-energy X-rays have high-penetration power to the matter [1]. Moreover, by using high-energy X-rays, we can measure light elements like lithium because inelastic scattering effect (Compton effect) relatively enhanced in the interaction between photons and the matter. This talk presents our recent studies using a commercial coin-type lithium battery, which have carried out at BL08W of SPring-8, Japan [2,3]. In these studies, we have developed a method for quantifying lithium from the line-shape of Compton scattered X-ray energy spectrum which called the S-parameter method. By using the S-parameter method, we nondestructively visualized the volume expansion of the electrodes during the charge-discharge cycle and the lithium distribution depending on the cycle rate on the VL2020 coin cell. Moreover, the change of lithium concentration on both anode and cathode during the cycle was revealed in-operando and in-situ conditions. Our technique which allows to directly measure the lithiation state in-operando and in-situ condition opens a new pathway for advanced characterization of the closed electrochemical cells. In this talk, we will also introduce a newly developed Compton scattering imaging system using a two-dimensional detector instead of a previous Ge solid-state detector.[1] M. Itou, Y. Orikasa, Y. Gogyo, K. Suzuki, H. Sakurai, Y. Uchimoto and Y. Sakurai, J. Synchrotron Rad., 22, 161-164 (2015).[2] K. Suzuki, A. Suzuki, T. Ishikawa, M. Itou, H. Yamashige, Y. Orikasa, Y. Uchimoto, Y. Sakurai and H. Sakurai, J. Synchrotron Rad., 24, 1006-1011 (2017).[3] K. Suzuki, R. Kanai, N. Tsuji, H. Yamashige, Y. Orikasa, Y. Uchimoto, Y. Sakurai and H. Sakurai, Condens. Matter, 3, 27 (2018).