Crystal structures of La3Li5M2O12 (M=Nb, Ta)

Hyooma, H.; Hayashi, K.

doi:10.1016/0025-5408(88)90264-4

Cited by 105 publications

(98 citation statements)

References 9 publications

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“…Despite a number of X-ray and neutron diffraction studies on powders and single crystals, the distribution of the Li cations among the various possible sites has been controversely discussed. Whereas according to Mazza [116] the C site is fully occupied with the two excess Li cations being accommodated by the octahedral voids, the structure following Hyooma's results [117] has all Li cations on octahedral positions with the tetrahedral C sites left completely empty. Based on the results of their neutron diffraction study, Cussen et al [74] rule out both suggestions and put forward a model in which 1/3 of the tetrahedral voids and 2/3 of the octahedral voids are filled with Li cations, translating into 20% of the Li cations adopting a tetrahedral and 80% an octahedral coordination.…”

Section: Crystalline Electrolytesmentioning

confidence: 99%

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

Wüllen¹,

Echelmeyer

Voigt

et al. 2010

Zeitschrift Für Physikalische Chemie

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Ionic TransportResearch on solid ionic conductors for use as electrolytes in all solid state batteries still constitutes a rather vivid branch of today's materials science. Despite enormous efforts, neither the development of a solid electrolyte fulfilling the key requirements such as mechanical stability and high ionic conductivity at ambient temperature has been successful nor has an extended understanding of the local Li coordination motifs in the often amorphous systems been obtained. In this contribution, recent progress both in the development of novel solid state electrolytes with high ionic conductivity and mechanical stability and in the characterization of the local Li coordination motifs in these electrolytes from our laboratory is presented. The work was performed as a project within the framework of the Collaborative Research Centre SFB 458 "Ionic Motion in Materials with Disordered Structures -From Elementary Steps to Macroscopic Transport". Results will be given for polymer electrolytes based on polyethylene oxide (PEO), polyphosphazene (PPZ) and polyacrylonitrile (PAN) with various Li salts, nano-composites of these polymer electrolytes and Al 2 O 3 as a ceramic filler, novel inorganic/organic hybrid electrolytes, in which a mixture of an ionic liquid and Li salt is confined within the pore system of a SiO 2 glass, and a crystalline electrolyte, Li 5 La 3 Nb 2 O 12 . Employing a range of advanced solid state NMR methodologies including dipolar based NMR techniques and pulsed field gradient (PFG) NMR and impedance spectroscopy we were able to obtain a detailed knowledge about the local Li cation coordination motifs and the mechanism of Li transport in these electrolytes. Especially the hybrid electrolytes and the salt rich PAN based polymer electrolytes were identified as rather promising materials which combine a high ionic conductivity and mechanical stability.

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Section: Crystalline Electrolytesmentioning

confidence: 99%

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

Wüllen¹,

Echelmeyer

Voigt

et al. 2010

Zeitschrift Für Physikalische Chemie

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“…This can be related to the fact that the early structural studies employed X-ray powder diffraction data [8][9][10], which makes location of the Li sites very difficult due to the low X-ray scattering factor of Li. More recently neutron diffraction structural studies have been reported for Li 5 La 3 M 2 O 12 (M=Nb, Ta) by Cussen [11].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and conductivities of the garnet-related Li ion conductors, Li5Ln3Sb2O12 (Ln=La, Pr, Nd, Sm, Eu)

2008

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“…[5][6][7] Recently, Weppner and co-workers discovered a formulation exhibiting up to 0.4 mS cm −1 at room temperature: Li 7 La 3 Zr 2 O 12 (also known as LLZO). [ 8 ] For comparison, conventional battery separators soaked in liquid electrolyte have a total conductivity of 0.4 mS cm −1 at room temperature.…”

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confidence: 98%

A Tale of Two Sites: On Defining the Carrier Concentration in Garnet‐Based Ionic Conductors for Advanced Li Batteries

Thompson

Sharafi

Johannes

et al. 2015

Advanced Energy Materials

152

159

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energy storage. While the primary strategy for improving performance has focused on electrode materials, the development of new solid state ionic conducting electrolytes has been overlooked as a potential means to revolutionize electrochemical energy storage. Examples of some of the technologies ( Figure 1 ) could include: (i) dual electrolyte Li-S batteries, (ii) solidstate batteries employing Li metal anodes, and (iii) all oxide, solid-state Li-ion batteries. Indeed, the need for ionic conducting solid-state electrolytes is clear, but relatively few have been identifi ed as promising candidates. The garnet mineral structure represents a family of complex oxides spanning a broad range of natural and synthetic compositions.Initial work identifi ed Li 5 La 3 M 2 O 12 (M = Nb 5+ , Ta 5+ ) as a promising formulation having a total conductivity of 0.04 mS cm −1 at room temperature. [5][6][7] Recently, Weppner and co-workers discovered a formulation exhibiting up to 0.4 mS cm −1 at room temperature: Li 7 La 3 Zr 2 O 12 (also known as LLZO). [ 8 ] For comparison, conventional battery separators soaked in liquid electrolyte have a total conductivity of 0.4 mS cm −1 at room temperature. [ 9 ] In LLZO, edge-sharing ZrO 6 octahedra and LaO 8 dodecahedra form an isotropic skeleton framework through which Li-ions and Li-ion vacancies form a percolative network of tetrahedral and distorted octahedral sites (Figure 1 ). In addition to high conductivity, LLZO has been reported to have the unprecedented combination of stability against metallic Li, and stability in dry air. [ 8,[10][11][12] LLZO is also referred to as a "stuffed" garnet because of its relatively high Li concentration (7 moles) compared to Li 3 La 3 M 2 O 12 . In the garnet family of materials, as the Li content is increased from Li = 3 mols toward Li = 7 mols, the ionic conductivity increases by several orders of magnitude. [ 13 ] At Li contents near Li = 6.5 mols, the cubic structure undergoes a reduction of symmetry to a tetragonal polymorph and the ionic conductivity again decreases. [ 14,15 ] A maximum in the ionic conductivity at room temperature has been observed for compositions near the critical Li concentration to stabilize the cubic phase. [16][17][18][19] As such, the majority of the work in the literature has focused on understanding how the cubic phase is stabilized at high Li concentrations. [14][15][16][17][18][19][20][21] However, the understanding of the fundamental parameters that control the Li conductivity has Solid electrolytes based on the garnet crystal structure have recently been identifi ed as a promising material to enable advance Li battery cell chemistries because of the unprecedented combination of high ionic conductivity and electrochemical stability against metallic Li. To better understand the mechanisms that give rise to high conductivity, the goal of this work is to correlate Li site occupancy with Li-ion transport. Toward this goal, the Li site occupancy is studied in cubic garnet as a function of Li concentration over the com...

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Crystal structures of La3Li5M2O12 (M=Nb, Ta)

Cited by 105 publications

References 9 publications

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

Synthesis and conductivities of the garnet-related Li ion conductors, Li5Ln3Sb2O12 (Ln=La, Pr, Nd, Sm, Eu)

A Tale of Two Sites: On Defining the Carrier Concentration in Garnet‐Based Ionic Conductors for Advanced Li Batteries

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