Why has phosphate bronze Na2 +xNb6P4O26 never been investigated as a material for energy storage?

Why has phosphate bronze Na2 +xNb6P4O26 never been investigated as a material for energy storage? Научная публикация

Журнал

Journal of Alloys and Compounds
ISSN: 0925-8388 , E-ISSN: 1873-4669

Вых. Данные

Год: 2026, Том: 1073, Номер статьи : 188948, Страниц : 12 DOI: 10.1016/j.jallcom.2026.188948

Ключевые слова

Na2+xNb6P4O26, Phosphate bronze, Synthesis conditions, Na+ migration, Discharge/charge capacity

Авторы

Skachilova M.G. ^1,2 , Podgornova O.A. ¹ , Tsydypylov D.Z. ¹ , Korotaev E.V. ³ , Fedorenko A.D. ^3,4 , Shapovalova A.A. ³ , Shindrov A.A. ^1,2

Организации

1	Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, 18 Kutateladze, Novosibirsk 630090, Russia
2	Department of Natural Sciences, Novosibirsk State University, 2 Pirogova, Novosibirsk 630090, Russia
3	Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 pr. Acad. Lavrent’iev, Novosibirsk 630090, Russia
4	Synchrotron Radiation Facility–Siberian Circular Photon Source "SKIF", Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Koltsovo, Russia

Информация о финансировании (1)

For the first time, the optimization of synthesis conditions, the study of Na+ mobility, and the evaluation of the electrochemical properties of sodium-niobium phosphate bronze Na2+xNb6P4O26 were carried out. The synthesis of phase-pure Na2+xNb6P4O26 was conducted at 900◦C for 2.5 h with 15 mol% and 5 mol% excess of Na and P sources, respectively. A detailed study of the structure of Na2+xNb6P4O26 showed the presence of four-, five- and six-coordinated bottlenecks for possible Na+ movements. The energy barriers to Na+ migration and ionic conductivity were evaluated using the bond valence site energy analysis, and kinetic Monte Carlo modeling implemented in the softBV program. 1D, 2D, and 3D pathways with energy barriers from 0.086 eV to 1.044 eV were detected. The theoretical and experimental ionic conductivity values are consistent with each other and are on the order of ~10-7 S cm- 1. Galvanostatic cycling of the Na2+xNb6P4O26/C composite was performed in Na cell. During the first discharge/charge, the capacity was ~330 mAh g-1/161 mAh g-1 (~14.0 Na+/7.0 Na+), and during subsequent discharges/charges, the capacity did not exceed 175/162 mAh g-1 (7.0–8.0 Na+). The contributions from surface-controlled capacitive reactions and diffusion-controlled processes were analyzed. According to the obtained data, the capacitive contribution predominates and accounts for ~75% at 0.1 mV s⁻¹ , remaining nearly unchanged with increasing scan rate (~79% at 1.0 mV s⁻¹). Ex situ XRD and XPS analyses revealed that the discharge/charge process proceeds via both (de)intercalation and conversion mechanisms.

Skachilova M.G. , Podgornova O.A. , Tsydypylov D.Z. , Korotaev E.V. , Fedorenko A.D. , Shapovalova A.A. , Shindrov A.A.
Why has phosphate bronze Na2 +xNb6P4O26 never been investigated as a material for energy storage?
Journal of Alloys and Compounds. 2026. V.1073. 188948 :1-12. DOI: 10.1016/j.jallcom.2026.188948

Поступила в редакцию:	27 февр. 2026 г.
Опубликована в печати:	25 июн. 2026 г.

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