Ionic Conductivity in Perovskite-Structured Solid Electrolytes

Perovskite-structured solid electrolytes, typically of the form ABO₃, have emerged as leading candidates for safe, high-energy-density all-solid-state batteries. Their framework, comprising a three-dimensional network of corner-sharing BO₆ octahedra with A-site cations in the interstices, offers continuous pathways for alkali-ion migration. Ionic conductivity in these oxides depends critically on the nature and distribution of point defects, dopant species on the A- or B-site, and the presence of interfaces such as grain boundaries or space-charge layers. Bulk conductivity values exceeding 10⁻³ S cm⁻¹ at ambient temperature have been achieved in optimally doped lanthanum lithium titanate (LLTO) and related compositions. However, grain boundaries often present a resistive bottleneck, as local cation depletion or structural disorder impedes long-range ion transport. Recent advances in atomic-scale characterisation and tailored synthesis—ranging from A-site disorder to compositionally complex multi-cation systems—have begun to mitigate interfacial resistance and to uncover the true mechanisms governing ionic mobility. These insights are pivotal for integrating perovskite electrolytes into practical devices, from thin-film solid-state batteries to composite polymer hybrids, and for extending their application beyond lithium to sodium and beyond.

Research from Nature Portfolio

Recent studies have leveraged aberration-corrected microscopy and machine-learning interatomic potentials to resolve the atomic structure of grain boundaries in Li₀.₃₇₅Sr₀.₄₃₇₅Ta₀.₇₅Zr₀.₂₅O₃. It was found that, unlike conventional La-rich titanates, these boundaries form a defective cubic perovskite interfacial phase rich in vacancies but free of lithium depletion, explaining their unusually low resistance. In a complementary investigation of Li₀.₃₃La₀.₅₆TiO₃, direct experimental and computational analysis of space-charge layers revealed these regions to be lithium-excess rather than deficient, permitting efficient ion transport. Attention thus shifts to Li-depleted grain-boundary cores as the principal source of interfacial resistivity in this archetype electrolyte.

Research from all publishers

A flux-mediated approach has produced single-crystal, A-site-disordered La₀.₅M₀.₅TiO₃ (M = Li, Na, K) nanorods with cubic perovskite symmetry and high aspect ratio. When embedded as fillers in polymer matrices, these nanorods double the ionic conductivity of the host electrolyte at room temperature by maximising the filler-polymer interface and minimising grain boundaries. Compositionally complex perovskite oxides incorporating multiple B-site cations have also been shown to surpass conventional doping limits: non-equimolar designs and thermal quenching yield conductivities more than 2.7 times higher than standard Li–Sr–Ta–Zr perovskites, with grain-boundary structures deliberately engineered to enhance interface-enabled transport. Finally, secondary ion mass spectrometry with isotope exchange has visualised lithium diffusion at grain boundaries in Li₀.₂₉La₀.₅₇TiO₃, quantifying boundary diffusion coefficients orders of magnitude lower than in the bulk and affirming the necessity of interface engineering to achieve practical conductivities in perovskite electrolytes.

Ionic Conductivity in Perovskite-Structured Solid Electrolytes publication trend

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

Technical terms

Perovskite structure: A crystal lattice of formula ABO₃ with corner-sharing BO₆ octahedra and A-site cations in interstitial sites.

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

Grain boundary: The interface between crystallites in a polycrystalline material, often exhibiting altered defect chemistry and transport properties.

Space-charge layer: A region near an interface where mobile ions accumulate or deplete, creating non-stoichiometric charge distributions affecting conductivity.

Activation energy: The energy barrier that ions must overcome to hop between lattice sites, influencing temperature dependence of conductivity.

References

1. Atomic-scale origin of the low grain-boundary resistance in perovskite solid electrolyte Li0.375Sr0.4375Ta0.75Zr0.25O3. Nature Communications (2023).
2. Atomic-scale study clarifying the role of space-charge layers in a Li-ion-conducting solid electrolyte. Nature Communications (2023).
3. Flux Synthesis of A‐site Disordered Perovskite La0.5M0.5TiO3 (M═Li, Na, K) Nanorods Tailored for Solid Composite Electrolytes. Advanced Science (2024).
4. Compositionally complex perovskite oxides: Discovering a new class of solid electrolytes with interface-enabled conductivity improvements. Matter (2023).
5. Visualization and evaluation of lithium diffusion at grain boundaries in Li 0.29 La 0.57 TiO 3 solid electrolytes using secondary ion mass spectrometry. Journal of Materials Chemistry A (2024).