Atomic insights into SEI mechanical response to early-stage lithium dendrite growth: A reactive molecular dynamics study

YR Huang and CH Chen, JOURNAL OF POWER SOURCES, 654, 237730 (2025).

DOI: 10.1016/j.jpowsour.2025.237730

Lithium metal, with high capacity and low electrochemical potential, is an attractive anode material, but its incompatibility with conventional electrolytes leads to serious dendrite formation. The solid electrolyte interphase (SEI) often forms a heterogeneous structure with poor mechanical properties. The heterogeneity promotes non-uniform lithium deposition, and the insufficient mechanical strength fails to prevent the development of dendrites. Characterizing SEI's mechanical properties and uniformity helps assess SEI's role in dendrite suppression; however, techniques like atomic force microscopy (AFM) nanoindentation struggle to capture real-time mechanical responses during dendrite formation. To clarify the interplay between the SEI and dendrite formation, we present a computational approach based on reactive molecular dynamics for simulating SEI formation and analyzing its mechanical characteristics. As two electrolytes - ethylene carbonate (EC) with 1M lithium hexafluorophosphate and triglyme (G3) with 1M lithium triflate - are examined in this study, we find that both SEIs share similar characteristics, such as thickness and charge distribution, but differ in mechanical behavior. The EC-derived SEI exhibits sawtooth-like force curves, and the G3-derived SEI shows uniform mechanical behavior. The effectiveness in distinguishing SEI characteristics across electrolytes reveals the approach's potential to accelerate the screening of new electrolyte formulations.

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