Entwicklung einer Zelle für in situ-Ramanspektroskopie an Lithium-Ionen-Batterien

Abstract

Electrolytes and electrodes play an important role for further improvements of lithium-ion batteries in concerning lifetime, safety and increase in the specific energy. To observe changes in the materials during operation in situ-measurements are used. Thereby it is possible to observe changes inside the batterie, while charging and discharging. This work reports the construction of an in situ-cell case for raman spectroscopy and the measurements with a commercial graphite electrode. Therefore a window of silica glass was build into a common batterie testcase. The objectiv of the raman spectrometer was orientend on the electrode with the help of an optical fiber and a superhead by Horiba®. The Laser was focused precisely with a translation stage. With this setting a high energy graphit electrode by Customcells® was analyzed. An electrolyte by Sigma-Aldrich® with a composition of 1:1 vol% EC:DEC with 1M LiPF6 was used. Based on the changes in the raman spectrum the lithium intercalation in the electrode was observed. For further informations, for example the decompostion products of the electrolyte, a Signal enhancing is necessary. Surface enhanced raman spectroscopy (SERS) with the use of silver nanopowder has been performed. Due to the signal overlap of the graphite and the surface stabilizer of the nanopowder, no changes in the raman signal were observed.