Atomic mechanism of lithium dendrite penetration in solid electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Computational Physics

Background:

• Lithium dendrite penetration in ceramic electrolytes causes mechanical failure and short circuits in solid-state lithium anode batteries.
• The precise mechanism of dendrite penetration remains debated due to limited in situ atomic-level observations.

Purpose of the Study:

• To elucidate the atomic-level mechanism of lithium dendrite nucleation and penetration in ceramic solid electrolytes using molecular dynamics simulations.
• To investigate the influence of stress accumulation and electrochemical factors on dendrite propagation and solid electrolyte fracture.

Main Methods:

• Molecular dynamics simulations were employed to model lithium dendrite nucleation and penetration.
• Analysis of stress accumulation, fracture mechanics (Griffith theory), and electrochemical impacts on fracture toughness.

Main Results:

• Dynamically generated lithium depositions cause internal stress accumulation, leading to solid electrolyte fracture at dendrite tips.
• Griffith theory is applicable, but local lithium ion concentration impacts fracture toughness.
• In polycrystalline electrolytes, dendrites propagate along grain boundaries, exhibiting mixed Mode I and Mode II fracture patterns.

Conclusions:

• The study provides atomic-level insights into lithium dendrite penetration mechanisms in solid electrolytes.
• Findings offer guidance for enhancing the performance and safety of solid-state lithium anode batteries by mitigating dendrite-induced failures.