Ultralow Young's Modulus Phosphosulfate Solid Electrolytes for High-Voltage All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• High-performance all-solid-state lithium batteries (ASSLBs) require mechanically soft solid-state electrolytes (SSEs) for intimate solid-solid interfacial contact.
• Existing oxide, sulfide, and halide SSEs struggle to balance mechanical softness, ionic conductivity, and high-voltage stability.

Purpose of the Study:

• To develop novel composite SSEs that overcome the limitations of current materials.
• To achieve excellent mechanical, electrochemical, and interfacial properties for ASSLBs.

Main Methods:

• Synthesized nanocrystalline/amorphous composite oxyanion-halide SSEs using dual-anion engineering.
• Incorporated sulfate (SO₄^2-) or phosphate (PO₄^3-) into a zirconium chloride matrix.
• Characterized mechanical properties (Young's modulus), ionic conductivity, and oxidative stability.

Main Results:

• Optimized sulfate-based and phosphate-based electrolytes exhibited low Young's moduli (∼0.4 GPa and ∼0.9 GPa, respectively).
• Achieved high room-temperature ionic conductivities (2.1 mS cm^-1 and 2.2 mS cm^-1).
• Demonstrated excellent cycling performance in ASSLBs with 4.6 V high-voltage cathodes (>90% capacity retention after 1000 cycles).

Conclusions:

• The developed composite SSEs provide a practical and cost-effective solution for ASSLBs.
• This dual-anion engineering approach resolves critical interfacial challenges in solid-state batteries.
• Enables next-generation high-energy-density batteries with improved safety and performance.