Lithiation-induced fracture of silicon nanowires observed by in-situ scanning electron microscopy
Journal
Nanotechnology
Journal Volume
31
Journal Issue
36
Date Issued
2020
Author(s)
Abstract
Silicon is expected to be a useful anode material in lithium ion batteries for future energy storage applications, because of its high theoretical charge storage density of Li+ ions. However, volume expansion due to lithiation fractures the Si anode material, leading to poor cycle stability of battery operation. The approaches to overcome the problem include using Si nanowires to relieve the stress induced by volume expansion and coating a protective layer on the Si anode to prevent delamination. In this study, we use in-situ scanning electron microscopy to monitor the morphological changes of 90 nm thick pristine Si nanowires and the Si nanowires coated with amorphous TiO2, respectively, during electrochemical lithiation. The results of in-situ observation show that both kinds of Si nanowires exhibit a larger thickness after 10 h lithiation and suffer fracture after 25 h. It is also found that the TiO2 layer is not strong enough to prevent Si nanowires from fracture. Since the TiO2 layer can not be elastically deformed, this surface shell fractures earlier in the lithiation process than pristine Si nanowires. Transformation of the crystalline Si nanowires to an amorphous phase and lithium composition detected in the nanowires support that the observed fracture indeed results from lithiation. © 2020 IOP Publishing Ltd.
Subjects
cycle stability; in-situ scanning electron microscopy; lithiation; lithium ion batteries; protective surface layer; silicon nanowires
SDGs
Other Subjects
Amorphous silicon; Anodes; Expansion; Fracture; Lithium-ion batteries; Nanocrystalline materials; Nanowires; Oxide minerals; Scanning electron microscopy; Titanium dioxide; Electrochemical lithiation; In-situ observations; Lithiation process; Lithium composition; Morphological changes; Protective layers; Silicon nanowires; Situ scanning electron microscopy; Silicon
Type
journal article