IN SITU SANS - A NEW METHOD TO NON-DESTRUCTIVELY INVESTIGATE LITHIATION PROCESSES IN POUCHBAG TYPE BATTERIES S. Seidlmayera, J. Hattendorffb, I. Buchbergerb, L. Kargea, H. A. Gasteigerb, and R. Gillesa a TU München, Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenberg-Str. 1, 85747 Garching, Germany b TU München, Chair of Technical Electrochemistry, Lichtenberg-Str. 4, 85748 Garching, Germany Small-angle scattering is a commonly used method to gain information about the nanostructure of the investigated materials (i.e. size, volume and shape of particles). SANS is well suited for studying any changes of these parameters inside closed battery cells under operation. Up to now only a few publications exist dealing with the SANS method for batteries and battery materials. This is mainly caused by the fact that only new developed batteries provide a reasonable thickness for transmission measurements necessary for the applied method. In 2012 Bridges et al. used a Li||Graphite coin cell for an in-situ SANS experiment, observing the growth of the anodic SEI-layer [1]. Nagao et al. used the method to investigate the Liintercalation mechanism in carbon host materials [2]. However, one major drawback in these experiments is that only cells with Li-metal as counter electrode were used. In our approach we assembled experimental cells consisting of the same anode and cathode materials as used in commercial cells and perform in-situ SANS experiment during charging/discharging. The cells are assembled as pouch bag or coffee bag cells. We report on our measurements with the SANS-1 instrument at Heinz Maier-Leibnitz Zentrum (MLZ), Garching. In-operando smallangle neutron scattering data of NMC||Separator||Graphite cells was collected during a complete charging and discharging cycle. In addition single battery components were measured separately to distinguish the various component signals. The in-operando data shows a variation of the integrated total scattering intensity in dependence of the transferred charge. The curve features are directly associated with the Figure 1: Integrated total scattering intensity vs. lithiation process of the cathode or anode transferred charge calculated as x(Li) and dV/dQ plot of materials. Work on modelling these lithiation the Voltage vs. transferred charge. kinetics as observed by SANS and correlating them with other techniques is in progress. References [1] A. Bridges et al., Journal of Physical Chemistry C, 116(14), 7701-7711 (2012). [2] M. Nagao et al., Journal of the Electrochemical Society, 153(5), A914-A919 (2006). _____________________________________________________________________________