A cost-effective, ionically conductive and compressible oxychloride solid-state electrolyte for stable...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• All-solid-state batteries (ASSBs) require inorganic solid-state electrolytes with high ionic conductivity (>1 mS cm⁻¹ at 25°C), excellent compressibility (>90% density under 250-350 MPa), and cost-effectiveness (<$50/kg).
• Current solid-state electrolytes often face challenges in meeting these combined requirements, hindering the commercialization of ASSBs.

Purpose of the Study:

• To develop a novel inorganic solid-state electrolyte that meets the critical performance and cost targets for ASSBs.
• To demonstrate the potential of this new electrolyte in a functional all-solid-state battery cell.

Main Methods:

• Synthesis and characterization of Li₁·₇₅ZrCl₄·₇₅O₀·₅ oxychloride solid-state electrolyte.
• Measurement of ionic conductivity, compressibility, and raw material cost.
• Fabrication and testing of a lab-scale ASSB using the developed electrolyte, a LiNi₀·₈Mn₀·₁Co₀·₁O₂ cathode, and a Li₆PS₅Cl-coated Li-In anode.

Main Results:

• The synthesized Li₁·₇₅ZrCl₄·₇₅O₀·₅ electrolyte exhibits an ionic conductivity of 2.42 mS cm⁻¹ at 25°C.
• It achieves 94.2% density under 300 MPa, demonstrating high compressibility.
• The estimated raw material cost is $11.60/kg, significantly below the target.
• The ASSB cell demonstrated a discharge capacity retention of 70.34% (70.2 mAh g⁻¹) after 2082 cycles at 1 A g⁻¹ and 25°C under 1.5 tons of stacking pressure.

Conclusions:

• The developed Li-Zr-O-Cl oxychloride solid-state electrolyte successfully meets the key performance metrics for ionic conductivity, compressibility, and cost-effectiveness.
• The proof-of-concept ASSB cell shows promising long-term cycling stability, validating the potential of this material for next-generation energy storage.