Li Ion Cells Comprising Lithiated Columnar Silicon Film Anodes, TiS₂Cathodes and Fluoroethyene Carbonate (FEC) as a Critically Important Component

Si electrodes are the most important high capacity substitutes of Li metal and carbon anodes in high energy density Li ion batteries, including those based on sulfur or air cathodes. In this study we examined amorphous columnar structure silicon film anodes prepared by sputtering in rechargeable Li ion battery prototypes based on TiS 2 cathodes. The choice of this cathode material enabled focusing on the examination of pre-lithiated Si films as anode candidates in alkyl carbonate electrolyte solutions. The effectiveness of fluoro-ethylene carbonate (FEC) as a co-solvent in alkyl carbonates/LiPF 6 solutions for good performance of silicon anodes was exhibited. Hundreds of cycles were demonstrated in full Li ion cells containing these components. The columnar morphology of these anodes is retained after 1000 cycles. Their surface chemistry, measured by EDS and XPS is discussed. The results of this work encourage further R&D efforts toward the use of amorphous silicon films as anodes in advanced rechargeable Li batteries.