An in situ system for simultaneous stress measurement and optical observation of silicon thin film electrodes

Here an in situ system is presented to simultaneously study the evolution of both morphology and stress in the silicon thin film electrode during lithiation and delithiation. Owing to the specific design with two observation windows in the in situ cell, both the curvature and color of the silicon thin-film electrodes upon lithiation and delithiation processes can be measured by multi-optical sensor and optical microscope. By such colorimetric method, the color evolution can be used to represent the thickness of silicon thin film electrode, and the quantitative relationship can be obtained by in situ atomic force microscope and optical microscopy experiments. Combining the real thickness with Stoney equation, the accurate stress of the Li_xSi film can be obtained during the electrochemical cycles.