Journal
JOURNAL OF POWER SOURCES
Volume 216, Issue -, Pages 131-138Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2012.04.105
Keywords
Silicon; Pattern; Thin film electrode; Lithium ion batteries; Atomic force microscopy; Shape
Funding
- CAS [KJCX2-YW-W26]
- NSFC [50730005]
- 973 project [201203932900]
- 863 project [2009AA033101]
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Silicon is the most promising high capacity anode material to replace graphite for developing next generation high energy density Li-ion batteries. In this approach, patterned amorphous and microcrystalline Si thin film electrodes (a-Si and mu c-Si) have been prepared by rf-sputtering and etched further by a reactive ion etching (RIE) system to form square-shape microcolumn electrodes with controllable size (5 x 5 mu m width, 500 nm height, aspect ratio of width/height is 10:1) and array distance (5 mu m). It has been found that the volume expansion and contraction of a-Si and mu c-Si are anisotropic, about 180% along vertical direction and 40% along lateral direction. The total volume variation changes linearly with the increase of lithium insertion content up to similar to 310% for a-Si and similar to 300% for mu c-Si. It occurs nearly reversibly. In addition, it is observed that the original square-shape Si column transforms into the domelike appearance after lithium insertion and changes into bowl shape after lithium extraction gradually. Radial-like curved cracks are formed after 5-10 cycles and the neighboring Si columns tend to merge together when the distance of the columns is less than 1 mu m. (C) 2012 Elsevier BM. All rights reserved.
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