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4. 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.

Author

Timusheva, Natalia B., Golubnichiy, Alexander A., Morozov, Anatolii V., Burov, Arseniy S., Aksyonov, Dmitry A., Savina, Aleksandra A., Markopolskii, Roman G., and Abakumov, Artem M.

Subjects
PHYSICAL & theoretical chemistry, SOLID electrolytes, X-ray powder diffraction, ENERGY density, TRANSMISSION electron microscopy, GARNET, ELECTROCHEMICAL electrodes
Abstract

All-solid-state batteries (ASSBs) with a garnet-type solid electrolyte have been considered promising alternatives to traditional batteries with a liquid organic electrolyte, due to their enhanced safety and ability to accommodate high energy density electrodes. In this study, we conducted a comprehensive investigation of the high-temperature chemical compatibility between the garnet-like Li6.4Ga0.2La3Zr2O12 (Ga-LLZO) electrolyte and high-energy-density Li-rich layered Li1.2Ni0.2Mn0.6O2 cathode (LNM). Our findings suggest that a high temperature reaction between the Li-rich cathode and Ga-LLZO occurs at 700-900oC depending on the form of reactants. This reaction results in the formation of La(Ni, Mn)O3 and Li2ZrO3 as the two main products, as confirmed by powder X-ray diffraction and transmission electron microscopy analysis. Li2ZrO3 was discovered for the first time as a reaction product, and its formation in the case of Li-rich layered cathode material was rationalized with DFT + U calculations. The results were also compared with those obtained for a typical layered high-energy-density cathode material LiNi0.8Mn0.1Co0.1O2 (NMC811). [ABSTRACT FROM AUTHOR]

Published
2025
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7. Reversible multielectron redox activity of the anti-NASICON-type phosphate LiNbV(PO4)3 towards lithium and sodium intercalation.

Author

Cherkashchenko, Ilia R., Panin, Rodion V., Dembitskiy, Artem D., Novichkov, Daniil A., Aksyonov, Dmitry A., Antipov, Evgeny V., and Khasanova, Nellie R.

Subjects
REVERSIBLE phase transitions, TRANSITION metals, DENSITY functional theory, ENERGY storage, X-ray diffraction
Abstract

The LiNbV(PO4)3 phosphate with the anti-NASICON structure (a = 12.126(1) Å, b = 8.6158(4) Å, c = 8.6959(6) Å, V = 908.5(1) Å3, S.G. Pbcn) has been synthesized using a Pechini sol–gel process. It exhibits reversible multielectron transitions versus Li and Na anodes. In a Li half-cell, it supports a 4e− transfer due to the activation of the Nb5+/Nb3+ and V4+/V2+ redox couples, being the first example of 4d metal redox transitions within the anti-NASICON framework confirmed by XANES measurements. X-ray diffraction performed in ex situ and operando regimes disclosed a single-phase mechanism of lithium (de)intercalation. In a Na half-cell, the material demonstrates reversible uptake of 2.77 Na+ ions. Density functional theory calculations revealed percolation barriers of ∼0.5–0.7 eV for Na+ hopping, thus supporting the activation of Na+ ion diffusion in the NbV(PO4)3 framework. This study introduces a new approach to improve anti-NASICON-structured electrode materials by utilizing redox transitions of 4d elements for energy storage. [ABSTRACT FROM AUTHOR]

Published
2024
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8. NaZr2(PO4)3 – a cubic langbeinite-type sodium-ion solid conductor.

Author

Marshenya, Sergey N., Scherbakov, Alexey G., Dembitskiy, Artem D., Golubnichiy, Alexander A., Trussov, Ivan A., Savina, Aleksandra A., Kazakov, Sergey M., Aksyonov, Dmitry A., Antipov, Evgeny V., and Fedotov, Stanislav S.

Subjects
DENSITY functional theory, SOLID electrolytes, THERMAL expansion, ACTIVATION energy, INFRARED spectroscopy
Abstract

The synthesis of langbeinite-type phosphates with small cations such as Li+ or Na+via a high-temperature solid-state reaction is a challenging task due to the predominant formation of a related NaSICON-type phase. This work reports on the synthesis route, crystal structure, thermal behavior, and Na-conductive properties of the langbeinite-type NaZr2(PO4)3 prepared by a mechanochemically activated ion-exchange reaction between hydrothermally prepared NH4Zr2(PO4)3 and NaNO3. The crystal structure of NaZr2(PO4)3 is refined based on X-ray diffraction data and validated by Fourier-transformed infrared spectroscopy. NaZr2(PO4)3 is found to be stable up to 730 °C, undergoing a transformation into the NaSICON phase with further heating. Notably, in the 25–500 °C range, the material shows negative thermal expansion. The Na+ conductivity within the range of 50–225 °C amounts to 1.7 × 10−8 S cm−1 at 50 °C and 1 × 10−6 S cm−1 at 225 °C with an activation energy of 0.44 eV, accompanied by a sufficiently low (∼10−12 S cm−1) electronic conductivity. The bandgap of 4.44 eV and the electrochemical stability window covering the 1.39–4.18 V vs. Na/Na+ range are calculated using density functional theory. The obtained results open up opportunities for designing langbeinite-structured phosphates as potential solid electrolytes for Na-ion batteries. [ABSTRACT FROM AUTHOR]

Published
2024
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13. NaGaPO4F – a KTiOPO4-structured solid sodium-ion conductor.

Author

Marshenya, Sergey N., Dembitskiy, Artem D., Fedorov, Dmitry S., Scherbakov, Alexey G., Trussov, Ivan A., Emelianova, Olga, Aksyonov, Dmitry A., Buzlukov, Anton L., Zhuravlev, Nikolai A., Denisova, Tatiana A., Medvedeva, Nadezhda I., Abakumov, Artem M., Antipov, Evgeny V., and Fedotov, Stanislav S.

Subjects
SOLID state batteries, SODIUM ions, X-ray powder diffraction, NUCLEAR magnetic resonance, SYNCHROTRONS, IONIC conductivity, EXCHANGE reactions, ION mobility, ELECTRON diffraction
Abstract

Advanced ionic conductors are crucial for a large variety of contemporary technologies spanning solid state ion batteries, fuel cells, gas sensors, water desalination, etc. In this work, we report on a new member of KTiOPO4-structured materials, NaGaPO4F, with sodium-ion conductivity. NaGaPO4F has been obtained for the first time via a facile two-step synthesis consisting of a hydrothermal preparation of an ammonia-based precursor, NH4GaPO4F, followed by an ion exchange reaction with NaNO3. Its crystal structure was precisely refined using a combination of synchrotron X-ray powder diffraction and electron diffraction tomography. The material is thermally stable upon 450 °C showing no significant structural transformations or degradation but only a ∼1% cell volume expansion. Na-ion mobility in NaGaPO4F was investigated by a joint experimental and computational approach comprising solid-state nuclear magnetic resonance (NMR) and density functional theory (DFT). DFT and bond-valence site energy (BVSE) calculations reveal 3D diffusion of sodium in the [GaPO4F] framework with migration barriers amounting to 0.22 and 0.44 eV, respectively, while NMR yields 0.3–0.5 eV that, being coupled with a calculated bandgap of ∼4.25 eV, makes NaGaPO4F a promising fast Na-ion conductor. [ABSTRACT FROM AUTHOR]

Published
2023
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14. NaGaPO4F – a KTiOPO4-structured solid sodium-ion conductor

Author

Marshenya, Sergey N., primary, Dembitskiy, Artem D., additional, Fedorov, Dmitry S., additional, Scherbakov, Alexey G., additional, Trussov, Ivan A., additional, Emelianova, Olga, additional, Aksyonov, Dmitry A., additional, Buzlukov, Anton L., additional, Zhuravlev, Nikolai A., additional, Denisova, Tatiana A., additional, Medvedeva, Nadezhda I., additional, Abakumov, Artem M., additional, Antipov, Evgeny V., additional, and Fedotov, Stanislav S., additional

Published
2023
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15. A Comprehensive Review of Defects Genealogy in Olivines: From the Mineral World to Modern Electrode Materials.

Author

Nazarov, Eugene E., Aksyonov, Dmitry A., Antipov, Evgeny V., and Fedotov, Stanislav S.

Subjects
*OLIVINE, *MINERALS, *ELECTROCHEMICAL electrodes, *MATERIALS science, *ELECTRODES
Abstract

The "Learning from nature" strategy is currently going through a renaissance period in modern materials science. Valuable experience gained by observing existing natural materials—minerals—paves the way towards design and modification of prospective functional materials for energy storage, which typically inherit the peculiarities of the parental minerals. The faults and flaws of the crystal structure—its defects—play a crucial role in determining both mechanical and electrochemical properties of the electrode materials. In this review, we endeavored to rethink the defect chemistry in triphylite-type positive electrode materials for metal-ion batteries and reflected on it from the perspective of their mineral olivine counterparts, thus establishing important correlations between point defects in olivine minerals and related electrode materials, their origin and formation processes. This work is meant to review geoscience and materials science perceptions of defects in triphylite-type electrode materials for Li- and Na-ion batteries. [ABSTRACT FROM AUTHOR]

Published
2023
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17. Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Author

Morozov, Anatolii V., primary, Moiseev, Ivan A., additional, Savina, Aleksandra A., additional, Boev, Anton O., additional, Aksyonov, Dmitry A., additional, Zhang, Leiting, additional, Morozova, Polina A., additional, Nikitina, Victoria A., additional, Pazhetnov, Egor M., additional, Berg, Erik J., additional, Fedotov, Stanislav S., additional, Tarascon, Jean-Marie, additional, Antipov, Evgeny V., additional, and Abakumov, Artem M., additional

Published
2022
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19. Retardation of Structure Densification by Increasing Covalency in Li-Rich Layered Oxide Positive Electrodes for Li-Ion Batteries

Author

Morozov, Anatolii V., Moiseev, Ivan A., Savina, Aleksandra A., Boev, Anton O., Aksyonov, Dmitry A., Zhang, Leiting, Morozova, Polina A., Nikitina, Victoria A., Pazhetnov, Egor M., Berg, Erik, Fedotov, Stanislav S., Tarascon, Jean-Marie, Antipov, Evgeny V., Abakumov, Artem M., Morozov, Anatolii V., Moiseev, Ivan A., Savina, Aleksandra A., Boev, Anton O., Aksyonov, Dmitry A., Zhang, Leiting, Morozova, Polina A., Nikitina, Victoria A., Pazhetnov, Egor M., Berg, Erik, Fedotov, Stanislav S., Tarascon, Jean-Marie, Antipov, Evgeny V., and Abakumov, Artem M.

Abstract

Because of the outstanding discharge capacity provided by oxygen redox activity, Li-rich layered oxide positive electrode materials for Li-ion batteries attract tremendous attention. However, there is still no full consensus on the role that the ionocovalency of transition metal (TM)–oxygen (O) chemical bonding plays in the reversibility of the oxygen redox as well as on both local crystal and electronic structure transformations. Here, we managed to tune the cationic/anionic redox contributions to the overall electrochemical activity using the xLi2RuO3-(1 – x)Li1.2Ni0.2Mn0.6O2 solid solutions as a model system possessing the same crystal structure and morphology as Li-rich layered oxides. We conclusively traced the whole cascade of events from increasing the covalency of the TM–O bond, suppressing irreversible oxygen oxidation to the generation of the reduced Mn species toward retarding the structure “densification” in the Li-rich layered oxides. The results demonstrate that enhancing the degree of covalency of the TM–O bonding is vitally important for anchoring the reversibility of the charge compensation mechanism occurring through partial oxygen oxidation.

Published
2022
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22. Revisited Ti2Nb2O9 as an Anode Material for Advanced Li-Ion Batteries

Author

Drozhzhin, Oleg A., primary, Grigoryev, Vladislav V., additional, Alekseeva, Anastasia M., additional, Samigullin, Ruslan R., additional, Aksyonov, Dmitry A., additional, Boytsova, Olga V., additional, Chernyshov, Dmitry, additional, Shapovalov, Victor V., additional, Guda, Alexander A., additional, Soldatov, Alexander V., additional, Stevenson, Keith J., additional, Abakumov, Artem M., additional, and Antipov, Evgeny V., additional

Published
2021
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32. Thermodynamics as a Driving Factor of LiCoO2Grain Growth on Nanocrystalline Ta-LLZO Thin Films for All-Solid-State Batteries

Author

Morozov, Anatolii V., Paik, Haemin, Boev, Anton O., Aksyonov, Dmitry A., Lipovskikh, Svetlana A., Stevenson, Keith J., Rupp, Jennifer L. M., and Abakumov, Artem M.

Abstract

All-solid-state batteries primarily focus on macrocrystalline solid electrolyte/cathode interfaces, and little is explored on the growth and stability of nanograined Li-garnet and cathode ones. In this work, a thin (∼500 nm) film of LiCoO2(LCO) has been grown on top of the polycrystalline layer of Ta-doped Li7La3Zr2O12(Ta-LLZO) solid electrolyte using the pulsed laser deposition (PLD) technique. Scanning transmission electron microscopy, electron diffraction, and electron tomography demonstrated that the LCO film is formed by columnar elements with the shape of inverted cones. The film appears to be highly textured, with the (003) LCO crystal planes parallel to the LCO/Ta-LLZO interface and with internal pores shaped by the {104} and {102} planes. According to density functional theory (DFT) calculations, this specific microstructure is governed by a competition between free energies of the corresponding crystal planes, which in turn depends on the oxygen and lithium chemical potentials during the deposition, indicating that thermodynamics plays an important role in the resulting LCO microstructure even under nonequilibrium PLD conditions. Based on the thermodynamic estimates, the experimental conditions within the LCO stability domain are proposed for the preferential {104} LCO orientation, which is considered favorable for enhanced Li diffusion in the positive electrode layers of all-solid-state batteries.

Published
2022
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34. Exploring the Origin of the Superior Electrochemical Performance of Hydrothermally Prepared Li-Rich Lithium Iron Phosphate Li1+δFe1−δPO4

Author

Drozhzhin, Oleg A., primary, Sobolev, Alexey V., additional, Sumanov, Vasiliy D., additional, Glazkova, Iana S., additional, Aksyonov, Dmitry A., additional, Grebenshchikova, Anastasia D., additional, Tyablikov, Oleg A., additional, Alekseeva, Anastasia M., additional, Mikheev, Ivan V., additional, Dovgaliuk, Iurii, additional, Chernyshov, Dmitry, additional, Stevenson, Keith J., additional, Presniakov, Igor A., additional, Abakumov, Artem M., additional, and Antipov, Evgeny V., additional

Published
2019
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37. “Hydrotriphylites” Li1–xFe1+x(PO4)1–y(OH)4y as Cathode Materials for Li-ion Batteries

Author

Sumanov, Vasily D., primary, Aksyonov, Dmitry A., additional, Drozhzhin, Oleg A., additional, Presniakov, Igor, additional, Sobolev, Alexey V., additional, Glazkova, Iana, additional, Tsirlin, Alexander A., additional, Rupasov, Dmitry, additional, Senyshyn, Anatoliy, additional, Kolesnik, Irina V., additional, Stevenson, Keith J., additional, Antipov, Evgeny, additional, and Abakumov, Artem M., additional

Published
2019
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40. Revisited Ti2Nb2O9as an Anode Material for Advanced Li-Ion Batteries

Author

Drozhzhin, Oleg A., Grigoryev, Vladislav V., Alekseeva, Anastasia M., Samigullin, Ruslan R., Aksyonov, Dmitry A., Boytsova, Olga V., Chernyshov, Dmitry, Shapovalov, Victor V., Guda, Alexander A., Soldatov, Alexander V., Stevenson, Keith J., Abakumov, Artem M., and Antipov, Evgeny V.

Abstract

Ti2Nb2O9with a tunnel-type structure is considered as a perspective negative electrode material for Li-ion batteries (LIBs) with theoretical capacity of 252 mAh g–1corresponding to one-electron reduction/oxidation of Ti and Nb, but only ≈160 mAh g–1has been observed practically. In this work, highly reversible capacity of 200 mAh g–1with the average (de)lithiation potential of 1.5 V vs Li/Li+is achieved for Ti2Nb2O9with pseudo-2D layered morphology obtained via thermal decomposition of the NH4TiNbO5intermediate prepared by K+→ H+→ NH4+cation exchange from KTiNbO5. Using operandosynchrotron powder X-ray diffraction (SXPD), single-phase (de)lithiation mechanism with 4.8% unit cell volume change is observed. OperandoX-ray absorption near-edge structure (XANES) experiment revealed simultaneous Ti4+/Ti3+and Nb5+/Nb4+reduction/oxidation within the whole voltage range. Li+migration barriers for Ti2Nb2O9along [010] direction derived from density functional theory (DFT) calculations are within the 0.15–0.4 eV range depending on the Li content that is reflected in excellent C-rate capacity retention. Ti2Nb2O9synthesized via the ion-exchange route appears as a strong contender to widely commercialized Ti-based negative electrode material Li4Ti5O12in the next generation of high-performance LIBs.

Published
2021
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45. Hydroxyl Defects in LiFePO4Cathode Material: DFT+Uand an Experimental Study

Author

Aksyonov, Dmitry A., Varlamova, Irina, Trussov, Ivan A., Savina, Aleksandra A., Senyshyn, Anatoliy, Stevenson, Keith J., Abakumov, Artem M., Zhugayevych, Andriy, and Fedotov, Stanislav S.

Abstract

Lithium iron phosphate, LiFePO4, a widely used cathode material in commercial Li-ion batteries, unveils a complex defect structure, which is still being deciphered. Using a combined computational and experimental approach comprising density functional theory (DFT)+Uand molecular dynamics calculations and X-ray and neutron diffraction, we provide a comprehensive characterization of various OH point defects in LiFePO4, including their formation, dynamics, and localization in the interstitial space and at Li, Fe, and P sites. It is demonstrated that one, two, and four (five) OH groups can effectively stabilize Li, Fe, and P vacancies, respectively. The presence of D (H) at both Li and P sites for hydrothermally synthesized deuterium-enriched LiFePO4is confirmed by joint X-ray and neutron powder diffraction structure refinement at 5 K that also reveals a strong deficiency of P of 6%. The P occupancy decrease is explained by the formation of hydrogarnet-like P/4H and P/5H defects, which have the lowest formation energies among all considered OH defects. Molecular dynamics simulation shows a rich structural diversity of these defects, with OH groups pointing both inside and outside vacant P tetrahedra creating numerous energetically close conformers, which hinders their explicit localization with diffraction-based methods solely. The discovered conformers include structural water molecules, which are only by 0.04 eV/atom H higher in energy than separate OH defects.

Published
2021
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48. Exploring the Origin of the Superior Electrochemical Performance of Hydrothermally Prepared Li-Rich Lithium Iron Phosphate Li1+δFe1−δPO4.

Author

Drozhzhin, Oleg A., Sobolev, Alexey V., Sumanov, Vasiliy D., Glazkova, Iana S., Aksyonov, Dmitry A., Grebenshchikova, Anastasia D., Tyablikov, Oleg A., Alekseeva, Anastasia M., Mikheev, Ivan V., Dovgaliuk, Iurii, Chernyshov, Dmitry, Stevenson, Keith J., Presniakov, Igor A., Abakumov, Artem M., and Antipov, Evgeny V.

Published
2020
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49. Tuning the Crystal Structure of A2CoPO4F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO4F.

Author

Fedotov, Stanislav S., Aksyonov, Dmitry A., Samarin, Aleksandr Sh., Karakulina, Olesia M., Hadermann, Joke, Stevenson, Keith J., Khasanova, Nellie R., Abakumov, Artem M., and Antipov, Evgeny V.

Subjects
*X-ray powder diffraction, *SCANNING transmission electron microscopy, *CRYSTAL structure, *ELECTRODE potential, *DIFFERENTIAL scanning calorimetry, *ACTIVATION energy
Abstract

Co‐containing fluoride‐phosphates are of interest in sense of delivering high electrode potentials and attractive specific energy values as positive electrode materials for rechargeable batteries. In this paper we report on a new Co‐based fluoride‐phosphate, LiNaCoPO4F, with a layered structure (2D), which was Rietveld‐refined based on X‐ray powder diffraction data [P21/c, a = 6.83881(4) Å, b = 11.23323(5) Å, c = 5.07654(2) Å, β = 90.3517(5) °, V = 389.982(3) Å3] and validated by electron diffraction and high‐resolution scanning transmission electron microscopy. The differential scanning calorimetry measurements revealed that 2D‐LiNaCoPO4F forms in a narrow temperature range of 520–530 °C and irreversibly converts to the known 3D‐LiNaCoPO4F modification (Pnma) above 530 °C. The non‐carbon‐coated 2D‐LiNaCoPO4F shows reversible electrochemical activity in Li‐ion cell in the potential range of 3.0–4.9 V vs. Li/Li+ with an average potential of ≈ 4.5 V and in Na‐ion cell in the range of 3.0–4.5 V vs. Na/Na+ exhibiting a plateau profile centered around 4.2 V, in agreement with the calculated potentials by density functional theory. The energy barriers for both Li+ and Na+ migration in 2D‐LiNaCoPO4F amount to 0.15 eV along the [001] direction rendering 2D‐LiNaCoPO4F as a viable electrode material for high‐power Li‐ and Na‐ion rechargeable batteries. The discovery and stabilization of the 2D‐LiNaCoPO4F polymorph indicates that temperature influence on the synthesis of A2MPO4F fluoride‐phosphates needs more careful examination with perspective to unveil new structures. [ABSTRACT FROM AUTHOR]

Published
2019
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