Interface Stability and Kinetics of Sulfide Electrolytes in all-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• All-solid-state batteries (ASSBs) offer enhanced safety and energy density over conventional batteries.
• Interfacial stability is a critical challenge for long-term cycling in ASSBs due to complex reactions.

Purpose of the Study:

• To perform a comprehensive computational thermodynamic analysis of sulfide-based solid electrolytes (SEs) and their interfaces in ASSBs.
• To evaluate the electrochemical stabilities of various interfaces, including cathode/SE, SE/interlayer, SE/coating, and anode/SE.

Main Methods:

• Computational thermodynamic analysis.
• Systematic evaluation of (electro)chemical stabilities at different interfaces.
• Kinetic analysis of lithium-ion migration.

Main Results:

• Phosphate and sulfide cathodes show high thermodynamic stability with sulfide SEs.
• Interlayers and coatings (e.g., phosphates, binary halides) improve interface stability and mitigate side reactions.
• Silicon incorporation in lithium-alloy anodes enhances stability, with greater effect at higher Si content.
• The LiₓSi/Li₆PS₅Cl interphase exhibits lower activation energy barriers for Li-ion migration.

Conclusions:

• Optimizing interfaces through appropriate cathode materials, interlayers, coatings, and silicon-rich anodes is crucial for stable ASSB cycling.
• Computational thermodynamics provides valuable insights for designing stable interfaces in ASSBs.
• Enhanced ionic transport at the anode interphase contributes to improved battery performance.