Nanofibrillar Si Helices for Low-Stress, High-Capacity Li + Anodes with Large Affine Deformations

Dimitrios A. Antartis, Haoran Wang, Ching Yen Tang, Huck Beng Chew, Shen J. Dillon, Ioannis Chasiotis

Research output: Contribution to journalArticle

Abstract

We report on the chemical lithiation of long microscale helices composed of densely packed amorphous silicon (aSi) nanofibrils, fabricated by glancing angle deposition (GLAD) through e-beam evaporation. In situ electron microscopy and companion finite element modeling demonstrate that the nanofibrillar structure of the aSi helices allows for 2 orders of magnitude faster effective rates for Li diffusion (D 0 = 10 -10 cm 2 /s) compared to solid aSi nanowires, while also averting fragmentation during lithiation. More importantly, it is shown that specific helical geometries can accommodate large, lithium-induced, volumetric expansions without shape distortion. A major advantage of the helical nanostructures is that the compressive force generated due to lithiation-induced expansion is an order of magnitude smaller than in straight nanocolumns that permanently buckle during lithiation. Thus, GLAD-fabricated films composed of dense periodic microscale helices with properly designed coil geometries are highly suitable for robust, high-capacity Li + anodes.

Original languageEnglish (US)
Pages (from-to)11715-11721
Number of pages7
JournalACS Applied Materials and Interfaces
Volume11
Issue number12
DOIs
StatePublished - Mar 27 2019

Keywords

  • chemical lithiation
  • glancing angle deposition
  • lithium ion batteries
  • nanosprings
  • silicon electrodes

ASJC Scopus subject areas

  • Materials Science(all)

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