Solid Electrolytes for Lithium-Ion Conductivity

Solid electrolytes have become central to the advancement of all-solid-state lithium batteries, offering enhanced safety, wider electrochemical windows and potential for greater energy density compared with liquid-based systems. These materials encompass a range of chemistries, including oxide, sulphide and phosphate families, each presenting distinct trade-offs in ionic conductivity, mechanical robustness and interfacial stability. Sulphide electrolytes such as lithium thiophosphates combine high room-temperature Li⁺ conductivity with soft mechanical properties, facilitating intimate electrode contact, whereas oxide ceramics exhibit superior air stability at the cost of more challenging processing. Glass and glass-ceramic formulations introduce amorphous networks or controlled nanocrystalline domains, tuning free volume and grain-boundary characteristics to promote rapid Li⁺ migration. Key conduction mechanisms include vacancy-assisted hopping, concerted diffusion of cation clusters and the paddle-wheel effect arising from coupled anion librations. Recent engineering strategies target structural motifs at the atomic scale—through hetero-nanodomains, dopant incorporation and tailored heat treatments—to achieve conductivities rivalling those of liquid electrolytes. Integration of these solid electrolytes into full-cell architectures demands attention to interfacial chemistry, mechanical compliance and scalable synthesis routes. Overall, the field continues to evolve through a synergistic interplay of advanced characterisation, computational modelling and materials design, advancing the global pursuit of safer, higher-performance energy storage.

Research from Nature Portfolio

Researchers have developed a glass-ceramic lithium thiophosphate with self-organised hetero-nanodomains that deliver a record Li⁺ conductivity of over 13 mS cm⁻¹ at room temperature. By controlling nucleation energy during nanocrystallisation, closely spaced grain boundaries enriched in charge carriers are formed, as revealed by cryogenic transmission electron microscopy and electron holography. Variable-temperature solid-state nuclear magnetic resonance confirms that these boundaries facilitate exceptionally rapid Li⁺ transport, enabling all-solid-state cells with high-energy-density composite cathodes operating stably at ambient conditions. Foundational work has also elucidated the atomic and electronic structures of binary Li₂S–P₂S₅ glasses, demonstrating how variations in PSₓ polyhedral units and Li–S polyhedral connectivity influence free volume and the electrostatic interactions that govern Li⁺ mobility. Density functional theory combined with reverse Monte Carlo modelling shows that control of edge-sharing between PSₓ and LiSᵧ clusters, without unfavourable electron transfer, is critical to maximising ionic conduction in these glass electrolytes.

Research from all publishers

Advanced functional materials studies have shown that room-temperature sintering of amorphous Li₃PS₄ solid electrolytes requires optimisation beyond simple porosity reduction. Coupled electrochemical impedance spectroscopy and focused ion beam scanning electron microscopy reveal that sintering pressure and duration must be tuned to balance microstructural densification with the preservation of ion-transport pathways. Carbon Energy investigations into AgCl-doped Li₇P₃S₁₁ demonstrate that dual doping can enhance ionic conductivity by over 80 per cent. Synchrotron X-ray diffraction, density functional theory and neural-network molecular dynamics uncover how Ag and Cl dopants modulate PS₄–P₂S₇ frameworks, increasing polyhedral flexibility and promoting the paddle-wheel effect. Complementary work on ion-conducting glasses reveals that molecular vibrations of PS₄³⁻ units correlate with concerted Li⁺ diffusion. Topological valence analysis identifies distinct Li⁺ environments whose populations rise upon partial crystallisation, offering new insights into the interplay between structure, dynamics and conductivity in thiophosphate glasses.

Solid Electrolytes for Lithium-Ion Conductivity publication trend

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

Technical terms

Solid electrolyte: A non-liquid ionic conductor that enables ion transport between battery electrodes without flammability risks.

Ionic conductivity: A measure of how readily ions migrate through a material under an electric field, typically expressed in mS cm⁻¹.

Glass-ceramic: A composite material containing both amorphous glassy phases and controlled nanocrystalline domains to optimise ionic pathways.

Dopant: An intentional impurity atom added to modify structural and electronic properties, often to enhance ionic mobility.

Grain boundary: The interface between crystalline domains in a polycrystalline material, which can either impede or enhance ion transport.

Paddle-wheel effect: A mechanism in which anion reorientations facilitate the migration of cations, lowering activation barriers for ion hopping.

References

1. Exploring dopant‐enhanced ionic conductivity of AgCl‐doped Li7P3S11 solid electrolytes: Integrating synchrotron Rietveld analysis, DFT, and ANN‐based molecular dynamics approaches. Carbon Energy (2024).
2. Room‐Temperature Sintering of Amorphous Thiophosphate Solid Electrolyte (Li3PS4): Coupling Morphological Evolution to Electrochemical Properties. Advanced Functional Materials (2023).
3. Self-organized hetero-nanodomains actuating super Li+ conduction in glass ceramics. Nature Communications (2023).
4. Structural and electronic features of binary Li2S-P2S5 glasses. Scientific Reports (2016).
5. Lithium Ion Transport Environment by Molecular Vibrations in Ion‐Conducting Glasses. Energy & Environmental Materials (2023).