High-Performance Li-SeS_x All-Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state lithium-sulfur batteries (ASSLBs) offer high energy density and safety but face challenges.
• Sluggish kinetics, low sulfur utilization, high interfacial resistance, and sulfur's insulating nature hinder ASSLB development.

Purpose of the Study:

• To enhance cathode utilization in ASSLBs by introducing selenium (Se) into sulfur (S) cathodes.
• To modify electronic and ionic conductivities using SeSx solid solutions for improved ASSLB performance.

Main Methods:

• Forming SeSx solid solutions within sulfur cathodes.
• Investigating SeSx-Li3PS4 composites with varying Se content (x = 3, 2, 1, and 0.33).
• Utilizing theoretical calculations to confirm electron density redistribution.

Main Results:

• Achieved interfacial ionic conductivities of 10^-6 S cm^-1 for SeSx-Li3PS4 composites.
• Demonstrated stable and highly reversible SeSx cathodes in sulfide-based ASSLBs.
• SeS2/Li10Ge2P12-Li3PS4/Li solid-state cells delivered >1100 mAh g^-1 capacity (98.5% theoretical) at 50 mA g^-1, stable for 100 cycles.
• High loading cells achieved areal capacities up to 12.6 mAh cm^-2.

Conclusions:

• Selenium incorporation into sulfur cathodes via SeSx solid solutions enhances conductivity and utilization in ASSLBs.
• This strategy provides a new pathway for developing high-performance sulfur-based cathodes for ASSLBs.
• Deepened understanding of Se-S solid solution chemistry in ASSLB systems.