Pore Collapse and Regrowth in Silicon Electrodes for Rechargeable Batteries

Published

April 21, 2015

Author(s)

Steven C. DeCaluwe, Bal Mukund NMN Dhar, Liwei Huang, Yuping He, Kaikun Yang, Jon P. Owejan, Yiping Zhao, A. Alec Talin, Joseph Dura, Howard Wang

Abstract

Structure and composition changes of an alumina capped amorphous silicon (a-Si) thin-film anode in a lithium half-cell are measured, in opernado, by neutron reflectivity (NR) and electrochemical impedance spectroscopy. The a-Si anode's thickness expands and retracts upon lithiation and delithiation, respectively, while maintaining its integrity and low (less than or equal to}1.6 nm) interfacial roughness throughout the cycling. NR data are analyzed to quantify the a-Si thickness and composition at various states of charge over six cycles, revealing an apparently non-linear expansion of the a-Si layer volume versus lithium content, agreeing with previous thin-film a-Si studies. However, a proposed pore collapse and re-growth (PCR) mechanism establishes that the solid domains within the porous Li_xSi expand linearly with Li content (8.48 cm³/mol-Li), similar to that of crystalline Si. In the PCR model, the porosity is first consumed by the expansion of the solid domains, after which the film as a whole expands. Porosity is reversibly re-stablished at 5-28% in the delithiated states. Additionally, the 3nm thick alumina protective layer covering the a-Si is observed to be an effective artificial solid electrolyte interphase (SEI), since it maintains its structural integrity, low interfacial roughness, and relatively small resistance and no additional spontaneously-formed SEI is observed.

Citation

Journal of Physical Chemistry C

Volume

17

Pub Type

Journals

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Keywords

Neutron Reflectometry, Battery, Amorphous Silicon, Porosity, Volume Expansion, Lithium, Artificial Solid Electrolyte Interphase

Citation

DeCaluwe, S. , Dhar, B. , Huang, L. , He, Y. , Yang, K. , Owejan, J. , Zhao, Y. , Talin, A. , Dura, J. and Wang, H. (2015), Pore Collapse and Regrowth in Silicon Electrodes for Rechargeable Batteries, Journal of Physical Chemistry C, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917218 (Accessed April 25, 2024)