Numerical investigation of microstructure and failure of lithiated silicon under biaxial tension

Su Chen, Hao Chen, Yinbo Zhao, Hiran Chathuranga, Aijun Du, Cheng Yan

Research output: Contribution to journalArticlepeer-review

Abstract

To develop high-capacity Li-ion batteries, volume expansion and material degradation of Si anodes have been attracting increasing attention. However, the effects of phase structures and geometrical constraints on the failure mechanism of lithiated Si have not been well understood. Considering phase boundaries formed during electrochemical cycles, we conducted molecular dynamics simulations to investigate the failure behaviour and microstructural evolution of single-phase and dual-phase (core–shell) lithiated Si structures when subjected to biaxial tensile stress. During lithiation, lithiated Si structures show a brittle-to-ductile transition. The brittle fracture is associated with nanoscale cavitation and void propagation. The ductility of lithiated Si structures increases with Li content due to the rearrangement of Li atoms. Compared with single-phase lithiated Si, dual-phase structures tend to fracture owing to inhomogeneous deformation and nanoscale cavitation. On the other hand, the ductility of lithiated Si decreases during delithiation, especially in dual-phase structures. This work provides a better understanding of the structure–property relationship of lithiated Si in charging-discharging cycles and strategies to improve the electrochemical performance of Si-based electrodes.

Original languageEnglish
Article number110764
JournalComputational Materials Science
Volume200
DOIs
Publication statusPublished - 2021 Dec

Keywords

  • Biaxial tension, Failure analysis
  • Dual-phase structures
  • Lithium-silicon alloys
  • Microstructural evolution
  • Molecular dynamics simulation

ASJC Scopus subject areas

  • Computer Science(all)
  • Chemistry(all)
  • Materials Science(all)
  • Mechanics of Materials
  • Physics and Astronomy(all)
  • Computational Mathematics

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