Solid-State Sodium-Ion Conductor Development

The pursuit of solid-state sodium-ion conductors has intensified in response to the need for abundant, low-cost, and safe energy storage solutions. Research efforts focus on achieving high room-temperature ionic conductivities, wide electrochemical stability windows and robust mechanical properties while maintaining compatibility with sodium metal and electrode materials. Key strategies include vacancy engineering, aliovalent doping, glass–ceramic formation and interface design. Computational screening and in situ characterisation tools have guided the discovery of novel frameworks—from sulphide and oxide hosts to oxysulphide and halide glasses—yielding conductivities that rival liquid electrolytes and offering new routes to scalable, energy-dense sodium solid-state batteries for grid and portable applications.

Research from Nature Portfolio

Recent studies have reported a family of oxysulphide glass electrolytes with compositions Na₃PS₄₋ₓOₓ that exhibit record critical current densities and enable pressure-induced sintering at ambient temperature to form fully homogeneous, mechanically robust glasses. These materials develop self-passivating interphases at the sodium-glass interface, supporting stable Na plating and stripping over extended cycling and demonstrating high performance in ambient-temperature sodium–sulphur cells. Another advance involved tungsten-substituted antimony sulphide, where partial Sb→W replacement generates sodium vacancies and induces a cubic phase, achieving conductivities up to 32 mS cm⁻¹ at 25 °C alongside improved humidity tolerance. Foundational computational–experimental work also introduced Na₁₀SnP₂S₁₂ as a superionic conductor with conductivities near 0.4 mS cm⁻¹, guiding further enhancement through Ge or Si substitution to optimise Na⁺ mobility.

Research from all publishers

A comprehensive review of inorganic solid electrolytes has emphasised structure design and interface engineering across oxide, sulphide and halide chemistries, highlighting routes to boost ionic conductivity, widen electrochemical windows and improve electrode compatibility via tailored particle architectures and interfacial coatings. Experimental investigations of anode–electrolyte interfaces have shown that interfacial stability depends both on the intrinsic electrochemical limits of the electrolyte and on the nature of the passivating decomposition products, with advanced microscopy and spectroscopy elucidating the mechanisms of interphase formation and mechanical degradation. In parallel, first-principles studies on Na₃SbS₄ have demonstrated that halide doping at the sulphur site modulates vacancy concentrations and bottleneck geometries, lowering Na⁺ activation energies to around 0.1 eV and providing a clear design pathway for defect-engineered conductors with enhanced room-temperature performance.

Solid-State Sodium-Ion Conductor Development publication trend

The graph below shows the total number of articles in solid-state sodium-ion conductor development across all publications each year (not limited to Nature Index journals).

Technical terms

All-solid-state sodium-ion battery (ASS-NIB): A battery in which sodium ions migrate through a solid electrolyte between solid electrodes, replacing liquid electrolytes to improve safety and stability.

Ionic conductivity: The measure of an electrolyte’s capacity to transport ions, expressed in siemens per centimetre (S cm⁻¹), critical for determining battery power performance.

Electrochemical stability window: The voltage range within which an electrolyte remains inert and does not undergo reduction or oxidation.

Solid electrolyte interphase (SEI): A passivating layer that forms at the electrode–electrolyte boundary, enabling reversible ion transport while blocking detrimental side reactions.

Vacancy: A lattice defect where an ion site is unoccupied, often introduced intentionally to facilitate faster ion migration.

References

1. Structure designing, interface engineering, and application prospects for sodium‐ion inorganic solid electrolytes. InfoMat (2024).
2. An electrochemically stable homogeneous glassy electrolyte formed at room temperature for all-solid-state sodium batteries. Nature Communications (2022).
3. Design and synthesis of the superionic conductor Na10SnP2S12. Nature Communications (2016).
4. Evaluating Electrolyte–Anode Interface Stability in Sodium All-Solid-State Batteries. ACS Applied Materials & Interfaces (2022).
5. Theoretical study on stability and ion transport property with halide doping of Na 3 SbS 4 electrolyte for all-solid-state batteries. Journal of Materials Chemistry A (2022).