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Issue 17, 2015
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Pore collapse and regrowth in silicon electrodes for rechargeable batteries

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Abstract

Structure and composition of an 11 nm thick amorphous silicon (a-Si) thin film anode, capped with 4 nm of alumina are measured, in operando, by neutron reflectivity (NR) and electrochemical impedance spectroscopy in a lithium half-cell. NR data are analyzed to quantify the a-Si thickness and composition at various states of charge over six cycles. The a-Si anode expands and contracts upon lithiation and delithiation, respectively, while maintaining its integrity and low interfacial roughness (≤1.6 nm) throughout the cycling. The apparently non-linear expansion of the a-Si layer volume versus lithium content agrees with previous thin-film a-Si anode studies. However, a proposed pore collapse and regrowth (PCRG) mechanism establishes that the solid domains in the porous LixSi film expand linearly with Li content at 8.48 cm3 mol−1 Li, similar to crystalline Si. In the PCRG model, porosity is first consumed by expansion of solid domains upon lithiation, after which the film as a whole expands. Porosity is reestablished at 5–28% upon delithiation. Data show that the alumina protective layer on the a-Si film functions as an effective artificial solid electrolyte interphase (SEI), maintaining its structural integrity, low interfacial roughness, and relatively small transport resistance. No additional spontaneously-formed SEI is observed in this study.

Graphical abstract: Pore collapse and regrowth in silicon electrodes for rechargeable batteries

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Publication details

The article was received on 22 Dec 2014, accepted on 17 Mar 2015 and first published on 23 Mar 2015


Article type: Paper
DOI: 10.1039/C4CP06017B
Citation: Phys. Chem. Chem. Phys., 2015,17, 11301-11312
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    Pore collapse and regrowth in silicon electrodes for rechargeable batteries

    S. C. DeCaluwe, B. M. Dhar, L. Huang, Y. He, K. Yang, J. P. Owejan, Y. Zhao, A. A. Talin, J. A. Dura and H. Wang, Phys. Chem. Chem. Phys., 2015, 17, 11301
    DOI: 10.1039/C4CP06017B

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