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MM: Fachverband Metall- und Materialphysik

MM 58: Topical Session Battery Materials IV

MM 58.1: Topical Talk

Donnerstag, 25. März 2010, 15:45–16:15, H6

Investigation of Microscopic Mechanisms and Mechanical Effects in Electrode Materials for Lithium-Ion Batteries — •Reiner Mönig — Karlsruhe Institute of Technology, Institute for Materials Research II, Postfach 3640, 76021 Karlsruhe, Germany

Lithium ion batteries are promising candidates for future electrical energy storage. Important components of batteries are the electrodes which critically determine energy and power density as well as reliability. In the electrodes, sufficiently high ionic and electronic conductivities often can only be achieved by using small particles. The small particles, which are often in the 100nm range, make detailed investigates complicated. For example, typical electrochemical characterization methods can only yield volume averaged data of a whole electrode. In this talk a technique for in situ scanning electron microscopy will be introduced. Observations recorded during Lithium insertion and extraction into individual Si nanowires and SnO₂ particles will be presented. The experiments give insight into the fundamental processes that control battery operation and reveal degradation mechanisms. Large volume expansions and the growth of cracks were frequently observed. In order to assess mechanical stresses arising from Li insertion/extraction, dedicated in situ substrate curvature experiments were performed. Mechanical stress seems to be an important factor controlling battery operation and degradation. In contrast to many chemical degradation mechanisms that can be suppressed by chemical means, mechanical stresses are inevitable and their consequences may be limiting factors for the applicability of novel battery materials.