Trimethylsilyl Compounds for the Interfacial Stabilization of Thiophosphate-Based Solid Electrolytes in...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Argyrodite-type Li6PS5Cl (LPSCl) shows promise as a solid electrolyte for all-solid-state batteries (ASSBs) due to its high ionic conductivity and flexibility.
• However, LPSCl suffers from electrochemical degradation at the electrolyte-cathode interface, hindering practical application.

Purpose of the Study:

• To improve the interfacial stability between sulfide-based solid electrolytes and cathode materials in ASSBs.
• To investigate the use of trimethylsilyl compounds as solid electrolyte additives.

Main Methods:

• Introduction of 2-(trimethylsilyl)ethanethiol (TMS-SH) as a solid electrolyte additive.
• Electrochemical testing of Li | LPSCl | LiCoO2 cells with TMS-SH additive.
• Analysis of the cathode-electrolyte interphase (CEI) layer formation.

Main Results:

• TMS-SH oxidatively decomposes during charging, forming a stable CEI layer.
• The TMS-SH-derived CEI layer effectively suppresses interfacial degradation between LPSCl and LiCoO2.
• The modified solid electrolyte enables superior electrochemical performance, achieving over 2000 cycles with 85.0% capacity retention.

Conclusions:

• Trimethylsilyl compounds, specifically TMS-SH, are effective additives for enhancing the interfacial stability of sulfide solid electrolytes in ASSBs.
• The formation of a stable CEI layer is crucial for improving the cycle life and performance of ASSBs.