Solid-State Electrolytes for Ionic Conductivity Applications

Solid-state electrolytes are ion-conducting solids designed to replace flammable organic liquids in rechargeable batteries and electrochemical devices. They encompass ceramic oxides, sulfides, glass–ceramics, polymer systems and complex metal hydrides. The principal aim is to achieve ionic conductivities of at least 10−3 S cm−1 at ambient temperature while ensuring chemical and electrochemical stability against high-voltage cathodes and alkali metal anodes. Strategies include crystal chemistry design to create fast-ion sublattices, exploiting dynamic anion reorientations and engineering defects or disorder to lower migration barriers. Nanocomposite approaches introduce insulating phases to induce space charge regions that enhance conductivity via interfacial effects. Key challenges remain in minimising interfacial resistance, maintaining mechanical integrity under cycling and widening the electrochemical window. Advances in spectroscopy, computational modelling and materials synthesis promise safer, higher-energy-density batteries for electric vehicles, grid storage and portable electronics by harnessing solid-state electrolyte technologies.

Research from Nature Portfolio

Recent studies have introduced superionic complex hydrides that combine high conductivity with stable interfaces. One work reports a lithium closo-borane conductor forming a eutectic mixture with conductivities above 6 × 10−3 S cm−1 at 25 °C and low resistance to lithium metal, enabling ultra-high-energy-density all-solid-state cells. Another investigation explores chelated magnesium borohydride–ethylenediamine complexes prepared by mechanochemistry, achieving ion conductivities up to 6 × 10−5 S cm−1 at 70 °C and demonstrating reversible magnesium plating and stripping. A further contribution characterises dynamic Ag+ migration in silver closo-borane frameworks, reporting millisiemens-per-centimetre conductivities at room temperature and highlighting cage-like anions in facilitating rapid ion transport. Together, these works establish cage hydride chemistry and tailored coordination environments as promising routes for next-generation solid electrolytes.

Solid-State Electrolytes for Ionic Conductivity Applications publication trend

The graph below shows the total number of articles in solid-state electrolytes for ionic conductivity applications across all publications each year (not limited to Nature Index journals).

Technical terms

Solid-State Electrolyte: A solid material that conducts ions and replaces liquid electrolytes in electrochemical devices.

Superionic Conductor: A material exhibiting liquid-like ionic mobility within a solid matrix, yielding high ionic conductivity.

Complex Hydride: A compound containing metal cations and complex hydrogen-based anions, often forming cage-like structures that facilitate ion movement.

Nanocomposite Electrolyte: A multiphase material combining ion-conducting and insulating domains at the nanoscale to exploit interfacial effects enhancing ion transport.

Space Charge Layer: A region at the interface of dissimilar materials where local charge imbalances alter ion distribution and mobility.

References

1. Deciphering the Origin of Interface‐Induced High Li and Na Ion Conductivity in Nanocomposite Solid Electrolytes Using X‐Ray Raman Spectroscopy. Advanced Energy Materials (2024).
2. Designing Highly Conductive Sodium‐Based Metal Hydride Nanocomposites: Interplay between Hydride and Oxide Properties. Advanced Functional Materials (2023).
3. A complex hydride lithium superionic conductor for high-energy-density all-solid-state lithium metal batteries. Nature Communications (2019).
4. Magnesium Ethylenediamine Borohydride as Solid-State Electrolyte for Magnesium Batteries. Scientific Reports (2017).
5. Multifunctionality of silver closo-boranes. Nature Communications (2017).