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).
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