Solid-State Sodium Battery Technologies

Solid-state sodium batteries harness abundant sodium resources to offer a sustainable alternative to lithium‐based systems, addressing cost and safety concerns associated with liquid electrolytes. These devices replace flammable organic solvents with solid electrolytes—ceramics, glasses or polymers—that enable high energy density, extended cycle life and improved thermal stability. Central to their performance is the development of fast sodium‐ion conductors, particularly NASICON‐type frameworks, which combine three‐dimensional diffusion pathways with robust chemical stability. Complementary strategies include composite electrolytes that integrate soft polymers with ceramic fillers to enhance mechanical resilience and interface engineering to suppress dendrite formation at sodium anodes. Recent advances have realised ionic conductivities approaching those of liquid systems at room temperature and have demonstrated scalable fabrication routes. Remaining challenges involve minimising interfacial resistance, optimising electrode–electrolyte compatibility and ensuring manufacturability of high‐performance cells for grid storage, electric vehicles and portable electronics.

Research from Nature Portfolio

Research into mixed polyanion solid electrolytes has yielded a comprehensive kinetic model for NASICON compositions, revealing that silicon‐rich variants exhibit peak sodium mobility and an exceptionally low activation barrier. Experimental impedance spectroscopy confirmed a record ionic conductivity at elevated temperatures, validating the predictive framework. Building on fundamental insights, high‐throughput first‐principles studies combined with targeted synthesis have mapped the compositional landscape of NASICON conductors. These efforts unlocked new solid electrolytes with ambient‐temperature conductivities exceeding one millisiemens per centimetre and established clear design rules linking average metal size and polyanion substitution to transport properties. In parallel, ultrasound‐assisted bonding techniques have been developed to create intimate contact between sodium metal and ceramic electrolytes, dramatically reducing interfacial impedance and enabling stable plating–stripping cycles with high critical current densities and prolonged cycling performance at room temperature.

Solid-State Sodium Battery Technologies publication trend

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

Technical terms

NASICON (Na Superionic Conductor): A crystalline framework of corner‐sharing polyhedra that provides three‐dimensional pathways for rapid Na+ transport.

Solid‐state electrolyte: An ionically conductive solid material that replaces liquid electrolyte to improve safety and enable high‐energy density.

Ionic conductivity: A measure of how readily ions migrate through an electrolyte, typically expressed in siemens per centimetre.

Interfacial resistance: The impedance to ion flow at the contact between electrode and electrolyte, often limiting power performance.

Dendrite: Filamentary metal growth that can form during plating, risking short circuits and cell failure.

References

1. Pressureless all‐solid‐state Na/S batteries with self‐supporting Na5YSi4O12 scaffolds. Carbon Energy (2023).
2. Fundamental investigations on the sodium-ion transport properties of mixed polyanion solid-state battery electrolytes. Nature Communications (2022).
3. Design principles for NASICON super-ionic conductors. Nature Communications (2023).
4. Improving the alkali metal electrode/inorganic solid electrolyte contact via room-temperature ultrasound solid welding. Nature Communications (2021).