Compatibility Integrated Sulfide-Based Cathode and Electrolyte for High-Energy Solid-State Sodium Batteries

Abstract

The scarcity of critical raw materials in lithium-ion batteries has driven increasing interest in alternative chemistries, such as sodium- based all-solid-state batteries. Among various solid electrolytes, sulfide-based Na₃PS₄ stands out for its high ionic conductivity and excellent formability. However, its poor interfacial compatibility with conventional high-voltage oxide cathodes remains a major limitation. In this study, we report the successful integration of amorphous Na₂MoS₄—a high-capacity, sulfide-compatible cathode—into Na₃PS₄-based all-solid-state sodium batteries. Benefiting from a moderate redox potential window (1.1–2.7 V vs. Na⁺/Na), Na₂MoS₄ exhibits excellent chemical and electrochemical compatibility with Na₃PS₄, as confirmed by structural and spectroscopic analyses. Further investigation reveals that intimate interfacial contact between both electrodes and the solid-state electrolyte is critical for achieving long-term cycling stability. Based on these insights, the optimized Na₁₅Sn₄ | Na₃PS₄ | Na₂MoS₄-Na₃PS₄-carbon nanofiber cell delivers a reversible capacity of ~372 mAh·g^–1 at 0.1 C and retains nearly 100% capacity over 450 cycles at 0.3 C. In situ impedance spectroscopy further confirms the stability of interfacial resistance throughout cycling. This work identifies Na₂MoS₄ as a highly promising sulfide cathode for high-energy, long-life sodium solid-state batteries and provides valuable design principles for future development of sulfide-based electrode-electrolyte interfaces in next-generation energy storage systems.

Keywords

Sodium batteries / Sulfide solid electrolyte / Na₂MoS₄ / Sulfide-based cathode / Solid-state batteries / Energy storage / Amorphous materials / Electrochemistry

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