Effect of Solvents on a Li₁₀GeP₂S₁₂-Based Composite Electrolyte via Solution Method for Solid-State Battery...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Solution processing of composite electrolytes is key for thin layers and high energy density in solid-state batteries.
• Understanding solvent and binder compatibility is crucial for utilizing the high ionic conductivity of sulfide solid electrolytes.
• Lithium10GeP2S12 (LGPS) is a promising superionic conductor for next-generation batteries.

Purpose of the Study:

• To systematically investigate the impact of solvent polarity on the processing of LGPS composite electrolytes.
• To evaluate the detrimental effects of oxygen, moisture, and air on solvent-electrolyte interactions.
• To identify optimal solvent-binder combinations for fabricating thin and high-performance LGPS-based solid electrolytes.

Main Methods:

• Systematic screening of eight aprotic solvents with LGPS to determine allowable polarity ranges.
• Exposure of solvent-LGPS mixtures to dry air, nitrogen, and water vapor to assess stability.
• Fabrication of a composite electrolyte using dimethyl carbonate (DMC) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP).

Main Results:

• Dimethyl carbonate (DMC) was identified as a suitable low-polarity solvent for LGPS processing.
• A thin (∼40 μm) LGPS-based composite electrolyte achieved an ionic conductivity of 2 mS·cm⁻¹.
• The fabricated electrolyte demonstrated stable cycling for over 450 hours at 0.5 mA·cm⁻² and withstood high current surges.

Conclusions:

• Solvent polarity plays a critical role in the processability of LGPS solid electrolytes.
• The combination of DMC and PVDF-HFP offers a viable route for manufacturing thin, high-performance composite electrolytes.
• This work paves the way for practical, high-energy-density solid-state batteries utilizing sulfide electrolytes.