Structural and Electrochemical Investigation during the First Charging Cycles of Silicon Microwire Array Anodes for High Capacity Lithium Ion Batteries

Enrique Quiroga-González; Jürgen Carstensen; Helmut Föll

doi:10.3390/ma6020626

Structural and Electrochemical Investigation during the First Charging Cycles of Silicon Microwire Array Anodes for High Capacity Lithium Ion Batteries

Materials (Basel). 2013 Feb 22;6(2):626-636. doi: 10.3390/ma6020626.

Authors

Enrique Quiroga-González¹, Jürgen Carstensen², Helmut Föll³

Affiliations

¹ Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, Kiel 24143, Germany.
² Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, Kiel 24143, Germany. jc@tf.uni-kiel.de.
³ Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstr. 2, Kiel 24143, Germany. hf@tf.uni-kiel.de.

Abstract

Silicon microwire arrays embedded in Cu present exceptional performance as anode material in Li ion batteries. The processes occurring during the first charging cycles of batteries with this anode are essential for good performance. This paper sheds light on the electrochemical and structural properties of the anodes during the first charging cycles. Scanning Electron Microscopy, X-ray diffractommetry, and fast Fourier transformation impedance spectroscopy are used for the characterization. It was found that crystalline phases with high Li content are obtained after the first lithiation cycle, while for the second lithiation just crystalline phases with less Li are observable, indicating that the lithiated wires become amorphous upon cycling. The formation of a solid electrolyte interface of around 250 nm during the first lithiation cycle is evidenced, and is considered a necessary component for the good cycling performance of the wires. Analog to voltammetric techniques, impedance spectroscopy is confirmed as a powerful tool to identify the formation of the different Si-Li phases.

Keywords: Li-ion batteries; Si anode; Si microwire array; Si-Li phases; high capacity; in situ impedance spectroscopy; solid electrolyte interface (SEI) formation.