Core-Shell Structured Composite Solid Electrolyte Enables High-Rate All-Solid-State Sodium Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state sodium batteries (ASSSBs) are promising for large-scale energy storage.
• Challenges remain in ionic transport across multi-scale interfaces, hindering battery performance.

Purpose of the Study:

• To develop a composite solid electrolyte (SE) that improves ionic transport and interfacial stability in ASSSBs.
• To investigate the chemo-mechanical failure mechanisms at multiscale interfaces.

Main Methods:

• Fabrication of a core-shell structured composite electrolyte using Na3PS4 (sulfide SE) as the core and Na2.25Y0.25Zr0.75Cl6 (halide SE) as the shell.
• Characterization of the composite SE's oxidative stability, ionic conductivity, and mechanical properties.
• Fabrication and testing of a homogeneous full-cell configuration using the composite SE.

Main Results:

• The core-shell composite SE exhibits high oxidative stability (4.0 V), ionic conductivity (0.44 mS cm⁻¹), and mechanical strength (Young's modulus of 9.19 GPa).
• The composite SE effectively mitigates chemo-mechanically-induced interfacial contact losses at the cathode.
• The homogeneous full-cell achieved a discharge capacity of 76.4 mAh g⁻¹ at 2.0 C, outperforming conventional designs.

Conclusions:

• The core-shell structured composite electrolyte offers a novel design strategy for functional solid electrolytes in ASSSBs.
• This design enhances interfacial stability and electrochemical performance.
• The study provides insights into chemo-mechanical failure mechanisms in ASSSBs.