Agglomeration Mechanism and a Protective Role of Al2O3 for Prolonged Cycle Life of Si Anode in Lithium-Ion Batteries

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Si, the high-capacity anode for Li-ion battery (LIB), has intrinsic 300% volume changes limiting its commercial application. The volume change leads to particle pulverization that results in loss of electrical contacts. Various nanostructures are proposed to avoid the pulverization, but the commercialization is still a distant future. Recently, Al2O3 has demonstrated its ability to enhance electrochemical cycling performance. However, a comprehensive mechanistic role of the Al2O3 has not been well-understood. Here, we have combined electrochemical and chemical agitation tests to propose two novel mechanisms: Si agglomeration and a protective role of the Al2O3. LiPF6, the common Li salt of the LIB electrolyte, decomposes and forms HF that etches the native oxide layer then forms a labile Si-H surface. Because of the labile Si-H surfaces, the Si particles agglomerate during the volume changes. The Si agglomeration has a detrimental effect on the cycling performance associated with the loss of electrical contacts. On the other hand, in the presence of the Al2O3, the Al2O3 consumes the HF, protecting the native oxide layer that resists the agglomeration. Thus, the Si particles with Al(2)o(3) are better-dispersed. The Al2O3 allows the better Si dispersion during electrochemical cycles, resulting in improved capacity retention.
Publisher
AMER CHEMICAL SOC
Issue Date
2018-04
Language
English
Article Type
Article
Keywords

SOLID-ELECTROLYTE INTERPHASE; ATOMIC LAYER DEPOSITION; SILICON ELECTRODES; FLUOROETHYLENE CARBONATE; PHOTOELECTRON-SPECTROSCOPY; COULOMBIC EFFICIENCY; ENHANCED LITHIATION; SURFACE-CHEMISTRY; PERFORMANCE; STABILITY

Citation

CHEMISTRY OF MATERIALS, v.30, no.10, pp.3233 - 3243

ISSN
0897-4756
DOI
10.1021/acs.chemmater.8b00145
URI
http://hdl.handle.net/10203/242638
Appears in Collection
MS-Journal Papers(저널논문)
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