Computational Characterization of β-Li₃PS₄ Solid Electrolyte: From Bulk and Surfaces to Nanocrystals

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• All-solid-state lithium-ion batteries are crucial for renewable energy storage, particularly in electric vehicles.
• Solid-state electrolytes offer enhanced safety and energy density compared to liquid electrolytes.
• Beta-lithium thiophosphate (β-Li3PS4) is a promising solid-state electrolyte candidate due to its stability and ionic conductivity.

Purpose of the Study:

• To investigate the structural and electronic properties of β-Li3PS4 surfaces using density functional theory.
• To understand the atomic structure of β-Li3PS4 surfaces, which is critical for ionic diffusion and chemical stability.
• To identify stable crystallographic planes and their relevance for battery component interfaces and ion migration.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Thermodynamic stability of bulk β-Li3PS4 was verified.
• Surfaces were computationally cleaved along various crystallographic planes for analysis.

Main Results:

• The thermodynamically stable structure of bulk β-Li3PS4 was confirmed with minor distortions.
• The (100) surface was identified as the most stable at 298 K, followed by (011), (010), and (210) surfaces.
• Wulff nanocrystals were computed, showing that growth along (100) and (011) directions aligns with experimental observations.

Conclusions:

• Stable β-Li3PS4 surfaces beyond (100) exist and are relevant for battery applications.
• These stable surfaces can form interfaces with other battery components.
• The porous structures of these surfaces can facilitate lithium-ion migration, enhancing battery performance.