Melt-Infusion-Induced Electrolyte Surface Coating Stabilized Sulfide-Based All-Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfide-based all-solid-state lithium metal batteries (ASSLBs) offer high energy density but suffer from interfacial degradation.
• This degradation impedes lithium-ion (Li+) transport and causes uneven lithium deposition, limiting battery performance and safety.

Purpose of the Study:

• To develop an artificial coating for sulfide solid-state electrolytes (SSEs) to mitigate interfacial issues in ASSLBs.
• To enhance Li+ transport, suppress lithium dendrite formation, and improve the overall stability and performance of ASSLBs.

Main Methods:

• A melt-infusion method was employed to apply lithium trifluorosulfonylimide (LiTFSI) as an artificial coating on Li5.5PS4.5Cl1.5 (LPSCl) particles.
• Experimental characterization and theoretical calculations were used to analyze the coating's effect on the solid electrolyte interphase (SEI) and interfacial properties.

Main Results:

• The LiTFSI coating effectively mitigated interfacial side reactions, promoting a LiF/Li3N-rich SEI.
• This enhanced SEI accelerated Li+ transport and suppressed lithium dendrite growth, achieving a critical current density (CCD) of 3.1 mA cm-2.
• Li-symmetric cells demonstrated stable operation for 900 hours at 2 mA cm-2.
• ASSLBs with coated SSEs achieved 90.2% capacity retention over 1000 cycles at 2C and stable cycling with high LiCoO2 loading (28.5 mg cm-2).

Conclusions:

• The proposed artificial coating strategy significantly improves the interfacial stability and electrochemical performance of sulfide-based ASSLBs.
• The LiF/Li3N-rich SEI is crucial for enabling high critical current densities and long-cycle life in these advanced battery systems.
• This approach holds promise for the practical application of safe and high-energy all-solid-state lithium metal batteries.