Herstellung und Charakterisierung von Siliziumnanostrukturen für Lithium-Ionen-Batterien

For the use as anodes in lithium-ion batteries, silicon nanostructures were synthesized with three different methods and characterized. a-Si thin films were deposited on substrates of varying roughness with PECVD. Oxide-free porous and non-porous SiNW were synthesized with metal-assisted chemical etching and functionalized with acrylic acid. SiNW with different diameters were grown via CVD. The degradation mechanisms were investigated on the basis of the electrochemical characterization. a-Si thin films delaminated depending on roughness and film thickness that led to the temporary emergence of Li15Si4 and a reduced coulombic efficiency. Porous SiNW exhibited a reduced volume expansion and therefore a higher coulomb efficiency and reduced occurrence of Li15Si4. The grown SiNW showed little differences in their electrochemical behaviour. This is due to the drastic change in morphology from individual SiNW to a porous layer