High-Performance Se-S Composite Cathode Rich in Defects for Wide-Temperature Solid-State Lithium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• All-solid-state lithium batteries (ASSLBs) offer enhanced safety.
• Rare-earth halide solid electrolytes (RE-HSEs) exhibit promising ionic conductivity, electrochemical stability, and deformability.
• Sulfur (S) cathodes offer high energy density but suffer from poor electronic conductivity.

Purpose of the Study:

• To synthesize and evaluate selenium-sulfur (Se$_{x}$S$_{1-x}$) composites as cathode materials for ASSLBs.
• To improve the electronic and ionic conductivity of sulfur cathodes.
• To investigate the electrochemical performance of ASSLBs utilizing RE-HSEs and Se$_{x}$S$_{1-x}$ cathodes.

Main Methods:

• Synthesis of Se$_{x}$S$_{1-x}$ composites via a melting method.
• Fabrication of ASSLBs using Li$_{3}$YBr$_{6}$ as the solid electrolyte and Se$_{x}$S$_{1-x}$ as the cathode.
• Electrochemical characterization including cycling stability, rate capability, and performance at various temperatures.

Main Results:

• Se$_{x}$S$_{1-x}$ composites demonstrated improved electronic and ionic conductivities due to Se introduction and melting-induced defects.
• ASSLBs with Se$_{x}$S$_{1-x}$ cathodes exhibited low polarization, good cycling stability, and excellent rate properties at room temperature.
• The assembled solid batteries showed stable cycling at -30°C and normal operation at 120°C.

Conclusions:

• Selenium-sulfur composites are effective cathode materials for enhancing ASSLB performance.
• The developed ASSLBs demonstrate robust electrochemical performance across a wide temperature range.
• This work highlights the potential of RE-HSEs and modified sulfur cathodes for safe and high-performance energy storage.