Comprehensive thermal analysis of surface films formed on lithium ion battery negative electrodes

Kessen, Dennis; Peschel, Christoph; Tautvydas, Bieliauskas; Winter, Martin; Nowak, Sascha; Wiemers-Meyer, Simon

Abstract

Poster Abstract Advanced Battery Power Conference 2023 Comprehensive thermal analysis of surface films formed on lithium ion battery negative electrodes Dennis Kessena,*, Christoph Peschela, Tautvydas Bieliauskasa, Martin Wintera,b, Sascha Nowaka, Simon Wiemers-Meyera a University of Münster, MEET Battery Research Center, Corrensstraße 46, 48149 Münster, Germany b Helmholtz-Institute Münster, IEK-12, FZ Jülich, Corrensstraße 46, 48149 Münster, Germany Thermal analysis is commonly used to investigate the thermal stability, the material safety or the composition of lithium ion battery materials.[1] Furthermore, the identification of evaporated and pyrolyzed decomposition products facilitates the structural elucidation of electrode interphase layers and incorporated electrolyte decomposition products.[2] In this study, a variety of methods including thermogravimetric analysis (TGA), evolved gas analysis (EGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) were used to investigate the electrodes of LiNi0.8Co0.1Mn0.1O2 |C SiOx (20 %) and LiNi0.6Co0.2Mn0.2O2 |C 1 Ah pouch cells. By monitoring the weight loss and the mass information of the evolving gases during continuous heating of the sample, TGA and EGA were utilized to determine thermal decomposition zones of the electrodes. Py-GC-MS was then used for a detailed analysis of the evolving gases in the respective decomposition zones. The influence of various film-forming additives on the interphases after electrochemical aging was thereby analysed. As the pre-analysis washing of electrodes with dimethyl carbonate showed a significant influence on the obtained results, different degrees of washing were evaluated. Furthermore, new methodological approaches using thermodesorption-gas chromatography-mass spectrometry and isotope labelling were used to gain deeper insights into the thermal decomposition of electrode material. This poster presents a comprehensive overview of the mentioned thermal methods for the analysis of lithium ion battery electrodes. References [1] Y. P. Stenzel, M. Börner, Y. Preibisch, M. Winter, S. Nowak, Journal of Power Sources 2019, 433, 226709. [2] R. Mogi, M. Inaba, Y. Iriyama, T. Abe, Z. Ogumi, Langmuir 2003, 19, 814. [3] T. Yoon, M. S. Milien, B. S. Parimalam, B. L. Lucht, Chemistry of Materials 2017, 29, 3237. [3]