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 language | English |
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Pages (from-to) | 14718-14726 |
Number of pages | 9 |
Journal | ACS Applied Energy Materials |
Volume | 4 |
Issue number | 12 |
DOIs | |
State | Published - Dec 27 2021 |
Keywords
- Si anodes
- chemo-mechanics
- electrochemical properties
- formation enthalpy
- lithiation
- stress effect