Origin of Lithium Dendrite Formation in Sulfide-Based Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium dendrite growth is a major challenge for sulfide-based electrolytes (SEs), particularly Li3PS4 (LPS), in lithium metal batteries.
• Understanding Li dendrite penetration mechanisms in SEs with high shear modulus is crucial but lacking.

Purpose of the Study:

• Investigate optimal Li0 deposition sites in various LPS configurations (crystalline, lithiated, degraded).
• Determine preferential interstitial Li states (Li0/Li+) using ionization levels.
• Elucidate the electrochemical-mechanical degradation mechanism in SEs.

Main Methods:

• Computational investigation of Li0 deposition on crystalline, lithiated, and degraded LPS structures.
• Analysis of ionization levels to identify preferential Li states.
• Evaluation of defect configurations (cracks, grain boundaries) for Li0 deposition propensity.

Main Results:

• Bulk LPS and solid electrolyte interphase (SEI) layers resist Li0 deposition.
• Defect sites like cracks and grain boundaries (GBs) promote Li0 deposition.
• Li dendrite initiation significantly increases defect electronic conductivities, accelerating electron transport and penetration.

Conclusions:

• Defects in SEs act as preferential sites for Li dendrite initiation and growth.
• Synergistic interactions between Li dendrite propagation and crack formation drive SE degradation.
• Findings offer new methods for predicting Li dendrite growth and inform SE engineering.