Ionic Conductivity in Solid-State Electrolyte Systems

Solid-state electrolytes enable ion transport without liquid media, offering enhanced safety, energy density and thermal stability compared with conventional liquid electrolytes. Ionic conductivity in these materials arises from the movement of charge carriers—typically Li⁺, Na⁺ or O²⁻—through ordered or disordered lattices. Key classes include oxide garnets, sulphide glass-ceramics, perovskite-related phases and halide antiperovskites. Transport efficiency depends on lattice symmetry, defect chemistry, grain-boundary resistance and activation energy for ion migration. Strategies to boost conductivity encompass aliovalent doping to introduce vacancies, lattice engineering to widen diffusion channels, nanostructuring to control interfaces and computational screening to discover novel compositions. The current challenge is to achieve conductivities above 10⁻³ S cm⁻¹ at ambient temperature while ensuring chemical and electrochemical stability in full cells. Advances in synthesis, characterisation and modelling are converging to deliver solid-state electrolytes suitable for next-generation all-solid-state batteries, enabling higher capacity, longer lifespan and improved safety.

Research from Nature Portfolio

Recent studies have demonstrated that subtle lattice manipulation in antiperovskite electrolytes can dramatically enhance Li⁺ mobility. Substituting a small fraction of [Li₂OH]⁺ clusters with potassium ions stabilises the cubic framework, contracts the lattice and lowers migration barriers, yielding ionic conductivities on the order of 4.5 × 10⁻³ mS cm⁻¹ at 25 °C and excellent capacity retention in Li‖LiFePO₄ all-solid-state cells at elevated temperature.

Comprehensive reviews of solid-state chemistry principles have clarified how composition, crystal structure and defect energies underpin ionic transport across oxide, sulphide and halide families. Advanced diffraction, imaging and spectroscopic techniques coupled with theoretical modelling have mapped ion-migration pathways and phase stability, guiding the rational design of materials with tailored diffusion channels and improved interfacial compatibility.

High-throughput computational screening combining bond-valence methods with density functional theory has identified β-Li₃PS₄ and its doped derivatives as leading candidates for fast Li⁺ conduction. Predictions of migration energy barriers, subsequently validated by molecular dynamics, established oxygen-doping schemes that boost room-temperature ionic conductivity, illustrating the power of data-driven discovery in electrolyte development.

Research from all publishers

A recent review of Ruddlesden–Popper perovskite oxide electrolytes highlights their intrinsic water resistance and layered structure, which support both oxygen-anion and lithium-ion transport. Control of interlayer spacing, A-site chemistry and grain-boundary architecture has yielded flexible films and bulk ceramics with conductivities exceeding 10⁻⁴ S cm⁻¹ at ambient conditions, pointing towards wearable and bendable energy storage.

Investigations of argyrodite Li₆PS₅X (X = Cl, Br, I) have elucidated the role of halide substitutional disorder and lattice polarisation in long-range Li⁺ diffusion. Broadband impedance spectroscopy and ⁷Li NMR relaxation distinguish rapid local cage-exchange processes from inter-cage jumps, revealing that inhibited inter-cage connectivity in the ordered iodide variant severely limits macroscopic conductivity, thereby underscoring the importance of dynamic lattice disorder for superionic behaviour.

Ionic Conductivity in Solid-State Electrolyte Systems publication trend

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

Technical terms

Ionic conductivity: Measure of a material’s ability to transport charged ions under an electric field, expressed in S cm⁻¹.

Solid-state electrolyte: A non-liquid medium—crystalline or amorphous—that conducts ions while physically separating electrodes.

Antiperovskite: Crystal structure in which cation and anion positions are inverted relative to the perovskite archetype, often enabling fast ion channels.

Garnet structure: A cubic framework (general formula A₃B₂C₃O₁₂) used in Li-ion conductors such as Li₇La₃Zr₂O₁₂, noted for high stability and conductivity when doped.

Ruddlesden–Popper perovskite: Layered oxide structure comprising alternating perovskite slabs and rock-salt layers, enabling tunable ion transport pathways.

Argyrodite: Family of halide-thiophosphate materials (Li₆PS₅X) characterised by cage-like frameworks that facilitate superionic diffusion.

Aliovalent doping: Substitution of host ions with different valence to introduce point defects (vacancies or interstitials) that promote ionic mobility.

References

1. Boosting lithium ion conductivity of antiperovskite solid electrolyte by potassium ions substitution for cation clusters. Nature Communications (2023).
2. Solid state chemistry for developing better metal-ion batteries. Nature Communications (2020).
3. High-throughput design and optimization of fast lithium ion conductors by the combination of bond-valence method and density functional theory. Scientific Reports (2015).
4. Recent advances and future perspectives of Ruddlesden–Popper perovskite oxides electrolytes for all‐solid‐state batteries. InfoMat (2024).
5. Substitutional disorder: structure and ion dynamics of the argyrodites Li 6 PS 5 Cl, Li 6 PS 5 Br and Li 6 PS 5 I. Physical Chemistry Chemical Physics (2019).