Stress-Dependent Chemo-Mechanical Performance of Amorphous Si Anodes for Li-Ion Batteries upon Lithiation

Mingchao Wang, Han Ye, Chenxi Zhai, Guang Yang

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Alloying-type anodes are significantly governed by their chemo-mechanical performance during the electrochemical cycling. The reaction-induced huge volumetric change of these anodes may cause material degradation and failure under mechanical constraints. Here, we investigate the stress-dependent lithiation behavior of amorphous Si (a-Si) anodes using molecular dynamics simulations. It is indicated that a-Si anodes can sustain higher hydrostatic stress than biaxial/uniaxial ones without the occurrence of mechanical failure. Thermodynamic and electrochemical calculations demonstrate that although the lithiation procedure also affects the thermodynamic stability of a-Si anodes, it is mainly dominated by the external mean stresses. Compressive stress is confirmed to destabilize a-Si anodes and further trigger their capacity fading. Compared with our atomistic simulations, previous continuum models underestimate the open-cell potentials of a-Si anodes, due to their ignored large volumetric deformation at higher stresses and Li concentrations. This computational study provides the intensive atomic-level understanding of the stress-dependent lithiation behavior of a-Si anodes.

Original languageEnglish
Pages (from-to)14718-14726
Number of pages9
JournalACS Applied Energy Materials
Volume4
Issue number12
DOIs
StatePublished - Dec 27 2021

Keywords

  • Si anodes
  • chemo-mechanics
  • electrochemical properties
  • formation enthalpy
  • lithiation
  • stress effect

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