NaCl interphase enables stable Na_2.85Sb_0.95W_0.05S_3.9Cl_0.1-based all-solid-state sodium batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state sodium (Na) batteries (ASSSBs) offer enhanced safety and cost-effectiveness.
• Developing stable sodium sulfide electrolytes with high Na+ ionic conductivity is critical for high-performance ASSSBs.

Purpose of the Study:

• To design and synthesize a novel tungsten (W) and chlorine (Cl) co-doped sodium sulfide solid electrolyte.
• To enhance the ionic conductivity and interfacial stability of sodium sulfide electrolytes for sodium metal anodes.

Main Methods:

• Melt-quenching combined with annealing process for electrolyte synthesis.
• Characterization of ionic conductivity and electrochemical stability.
• Fabrication and testing of Na/electrolyte/Na symmetric cells and TiS2/electrolyte/Na ASSSBs.

Main Results:

• Achieved a Na+ ionic conductivity of 12.66 mS cm-1 in the W-Cl co-doped Na2.85Sb0.95W0.05S3.9Cl0.1 electrolyte, a significant increase from the undoped material.
• An in situ formed NaCl-based interphase layer effectively suppressed interfacial side reactions with the sodium metal anode.
• Demonstrated stable cycling over 800 h in a symmetric cell and achieved 81.6% capacity retention after 100 cycles in a TiS2-based ASSSB.

Conclusions:

• Tungsten and chlorine co-doping is a viable strategy to enhance the performance of sodium sulfide solid electrolytes.
• The developed electrolyte exhibits high ionic conductivity and excellent interfacial stability, paving the way for practical ASSSBs.