Double sodium fluorides as candidates for solid electrolytes and cathode protective coatings: Computational study and experimental verification
Daniil M. Chernyshov, Anatoly Volkov, Sergey N. Marshenya, Alexander A. Golubnichiy, Konstantin A. Lyssenko, Stanislav S. Fedotov, Dmitry A. Aksyonov
https://doi.org/10.1016/j.jallcom.2026.188312
The current study by Daniil Chernyshov, Dr. Dmitry Aksyonov and colleagues is dedicated to the computational and experimental investigation of double sodium rare-earth fluorides (β-NaYF4 and β-NaLaF4) as candidates for solid electrolytes and cathode protective coatings in all-solid-state sodium batteries. DFT calculations were combined with solid-state synthesis, single-crystal growth, and electrochemical impedance spectroscopy. The results showed that β-NaLaF4 exhibits a wide electrochemical stability window (up to ~5.4 V vs. Na+/Na), strong electronic insulation, low Na+ migration barriers (~0.3–0.4 eV), and stable, well-adhered interfaces with sodium metal. Experimental measurements confirmed a room-temperature ionic conductivity of ~10-5 mS cm-1, sufficient for thin cathode coatings. Aliovalent Ca doping in powder samples suppressed conductivity due to simultaneous substitution at Na and La sites, while single crystals grown from a eutectic melt successfully introduced Na vacancies, demonstrating a viable route to enhance ionic transport. The work highlights β-NaLaF4 as a promising protective coating material and outlines defect-engineering strategies for future solid-electrolyte applications.
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We are pleased to announce the X international school-conference of young scientists! The conference will take place November 14 to 18, 2025. This year's theme will be "Electrode Materials: Bridging Theory and Experiment".
Key dates:
Registration and abstract submission: August 31, 2025
Acceptance notice: September 5, 2025
Fee payment: September 15, 2025
We look forward to seeing you at our event in November! See how it went on the computational track last year: https://storion.ru/news/icys-2024
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Arseniy Burov, a PhD student in our research group, has been awarded a scholarship of the President of the Russian Federation! He was selected from over 4,500 applicants, which confirms the excellence of his work. Arseniy conducts computational research in the field of solid electrolytes and cathode materials for metal-ion batteries.
The list of Arseniy's publications so far:
- Burov, A. S., Boev, A. O., Abakumov, A. M., & Aksyonov, D. A. et al. Mechanism of Li+ charge transfer at Li/Li 7 La 3 Zr 2 O 12 interfaces: A density functional theory study // Physical Review B. – 2024. – V. 109. – №. 4. – P. 045305.
- Timusheva, N. B., Golubnichiy, A. A., Morozov, A. V., Burov, A. S., Aksyonov, D. A., Savina, A. A., ... & Abakumov, A. M. Chemical compatibility at the interface of garnet-type Ga-LLZO solid electrolyte and high-energy Li-rich layered oxide cathode for all-solid-state batteries // Scientific Reports. – 2025. – V. 15. – №. 1. – P. 241.
- Moiseev, I., Golubnichiy, A., Pavlova, A., Burov, A., Boev, A., Komayko, A., ... & Abakumov, A. M. The rivet effect: a new insight into improving structural stability in Mg-doped Ni-rich single-crystal layered oxide cathodes for Li-ion batteries // Journal of Materials Chemistry A. – 2025.
Congratulations from all the members of the research team to Arseniy on his success! We wish him all the best in his future scientific endeavors!
More information about the scholarship: https://aspirant.extech.ru/
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Origin of capacity retention in Ti-doped LiCoO2 : An AIMD study of Ti segregation effects on antisite defects, oxygen vacancies, and Li-ion charge transfer at the LiCoO2 / EC interface
A. Boev, D. Aksyonov
https://doi.org/10.1016/j.apsusc.2025.163162
The current study by Dr. Anton Boev and Dr. Dmitry Aksyonov is dedicated to the investigation of the effect of Ti doping on the surface stability of LiCoO2 (LCO) cathode material in lithium-ion batteries, particularly at high voltages. DFT and AIMD methods were used; for the first time, Ti segregation and its associated effects were analyzed with explicit consideration of the solvent, utilizing thermodynamic integration via the AIMD method.
The results showed that Ti segregation suppresses the formation of oxygen vacancies and promotes the appearance of anti-site defects. It also reduces the energy required to form a lithium vacancy, which stabilizes the surface. However, titanium slightly increases the barrier to the migration of lithium ions. Explicit solvent models have confirmed the importance of considering adsorption effects in order to accurately describe charge transfer processes.
The full text can be found here.
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