How Grain Boundaries Impede Lithium-Ion Diffusion and Induce Dendrite Growth: Insights from First-Principle...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Grain boundaries (GBs) in solid-state electrolytes are implicated in impeding ion transport and promoting dendritic growth.
• Existing experimental and theoretical methods face challenges in detailing ion diffusion and dendrite formation at GBs.

Purpose of the Study:

• To investigate the atomic-level mechanisms behind detrimental phenomena caused by grain boundaries in solid-state electrolytes.
• To elucidate the role of defects and electronic properties at GBs in ion and electron behavior.

Main Methods:

• Combined deep potential molecular dynamics (DPMD) simulations with density functional theory (DFT) calculations.
• Analyzed ion and electron trapping and accumulation at grain boundary regions.

Main Results:

• DFT and DPMD simulations identified abundant defects and high reducibility in GB regions.
• Ions and electrons were observed to be trapped and accumulate within GBs.
• This accumulation was found to impede bulk ion diffusion and increase the likelihood of lithium ion reduction.

Conclusions:

• Grain boundaries in solid-state electrolytes contribute to ion transport limitations and lithium dendrite formation.
• Defect-rich and reducible GB regions facilitate ion and electron accumulation, exacerbating these issues.
• Understanding these GB mechanisms is crucial for developing safer and more efficient solid-state batteries.