On the Structures of Alkali Polyaluminates

Yamaguchi, Goro; Suzuki, Kazuyuki

doi:10.1246/bcsj.41.93

Cited by 157 publications

(52 citation statements)

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“…The name fl"-alumina was first used by Yamaguchi & Suzuki (1968) for the compound NaEO.5A120 3 (or KzO.5AI203), because the crystal structure was substantially similar to that of fl-alumina, Na20.11Al20 3. It was later found that the fl"-alumina phase is considerably stabilized by the addition of a small amount of MgO and even single crystals have been prepared (Bettman & Peters, 1969;Kummer, 1972).…”

Section: Introductionmentioning

confidence: 99%

Irradiation-induced defects in β''-alumina examined by 1 MV high-resolution electron microscopy

Matsui¹,

Horiuchi²

1981

Acta Cryst Sect A

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The defect blocks formed in fl"-alumina by electron irradiation are examined by 1 MV high-resolution electron microscopy. In order to explain the fact that two distinctly different types of defect images appear even in a single 1 MV micrograph, a new structural model is constructed in place of the two models so far Breported. In the model proposed, two spinel-like blocks on either side of the eliminated conduction plane are those expected from the spinel structure.

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Section: Introductionmentioning

confidence: 99%

Irradiation-induced defects in β''-alumina examined by 1 MV high-resolution electron microscopy

Matsui¹,

Horiuchi²

1981

Acta Cryst Sect A

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“…-Beta alumina is used as the solid electrolyte in sodium/sulphur cells because of its exceptionally high Na + ion conductivity and negligibly low electronic conductivity [1][2][3][4][5]. It has the approximate formula Na 2 0.11 A1 2 0 3 and the structure (hexagonal, P6 3 /mmc) consists of layers of loosely bonded sodium ions between spinel-type blocks of aluminium and oxygen ions [6][7][8] as shown in figure 1. The mobility of the sodium ions within these planes is extremely high.…”

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confidence: 99%

“…This is preferred for use as an electrolyte because of its superior conductivity (~ 0.2 ohm -1 .cm" 1 at 350 °C compared to ~ 0.05 ohm -1 .cm -1 for the beta form). It has three spinel blocks per unit cell related by a threefold screw axis, compared to the two related by a twofold screw axis in beta alumina [8,9], and has a formula approximating to Na 2 0.5 A1 2 0 3 . This is a highly defective structure, the excess sodium relative to the beta alumina formula being compensated by aluminium ion vacancies.…”

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confidence: 99%

The Deterioration of Beta Alumina During Electrolysis

Demott¹,

Redfern²

1976

J. Phys. Colloques

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Résumé. -La raison principale de la défaillance de l'électrolyte céramique d'alumine béta dans des éléments sodium-soufre est le départ de la conduction électronique à travers l'électrolyte, avec la réduction du rendement faradique qui en résulte, suivie, dans certains cas, de la défaillance complète de l'élément. A cette phase finale le sodium métallique aura pénétré dans la céramique.Il a été suggéré que cette pénétration résulte de la propagation des fissures, mais on a remarqué que l'électrolyte se fonce fortement avant cette phase finale. Pour établir le rôle de ce brunissement dans le processus de défaillance, on a examiné par thermoluminescence la présence de centres colorés.Abstract. -The major cause of the failure of beta alumina ceramic electrolyte in sodium/ sulphur cells is the onset of electronic conduction through the electrolyte with a consequential reduction in Faradaic efficiency followed, in some cases, by complete failure of the cell. At this final stage sodium metal has penetrated the ceramic.Although crack propagation has been suggested as the cause of this penetration, it has been observed that the electrolyte darkens significantly before this final stage. In order to establish the role of this darkening in the failure sequence, the existence of colour centres has been examined by thermoluminescence.

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“…6). The β -and β "-alumina are non-stoichiometric compounds with hexagonal P6 3 /mmc (β -alumina) [130,131] and rhombohedral R3m (β "-alumina) [132,133] crystal structures, respectively. These structures have a twodimensional character.…”

Section: Methodsmentioning

confidence: 99%

Separators - Technology review: Ceramic based separators for secondary batteries

Nestler¹,

Schmid²,

Münchgesang³

et al. 2014

AIP Conference Proceedings

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Abstract. Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ("Energiewende") was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membranethe separator -as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based separators. Two prominent examples, the lithium-ion and sodium-sulfur battery, are described to show the current stage of development. New routes are presented as promising technologies for safe and long-life electrochemical storage cells.

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On the Structures of Alkali Polyaluminates

Cited by 157 publications

References 0 publications

Irradiation-induced defects in β''-alumina examined by 1 MV high-resolution electron microscopy

Irradiation-induced defects in β''-alumina examined by 1 MV high-resolution electron microscopy

The Deterioration of Beta Alumina During Electrolysis

Separators - Technology review: Ceramic based separators for secondary batteries

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