Berlin 2012 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.35: Poster
Monday, March 26, 2012, 17:00–19:00, Poster B
Silicon nanowires as anode electrodes for lithium ion batteries — •Gibaek Lee1,2, Stefan L Schweizer2, and Ralf B Wehrspohn1,2 — 1Fraunhofer Institute for Mechanics of Materials Halle — 2Martin-Luther-University Halle-Wittenberg
It has been known for some time that silicon can incorporate large amounts of Li with a specific capacity of 4200 mAh/g, about a factor of 11 larger than for state of the art graphite anodes. However, silicon and silicon-based negative electrodes exhibit huge volume expansion (ca. 270%) during lithium insertion and extraction, resulting in mechanical disintegration of electrode and rapid capacity fading. One way to overcome the problem of large volume expansion is to design three-dimensional porous electrode structures with sufficient porosity to accommodate the volume expansion. In this study, we prepared oriented silicon nanowire arrays (SiNWs) on n-type silicon substrate by metal assisted chemical etching in aqueous HF solution containing AgNO3. In addition, to reduce the usage of thick silicon substrates and extend applications of silicon micro/nanostructures on various substrates, we have developed ways to detach these SiNWs from bulk silicon substrate because particularly, the contribution of silicon wafer substrate could not be excluded from the capacity of the anode substrate.