Synthesis and Raman micro-spectroscopy investigation of Li7La3Zr2O12

Tietz, Frank; Wegener, T.; Gerhards, Marie-Theres; Giarola, Marco; Mariotto, G.

doi:10.1016/j.ssi.2012.10.021

Cited by 141 publications

(128 citation statements)

References 15 publications

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“…In addition, the Raman spectra were consistent with the spectra of cubic LLZTO reported by Thompson et al (2014). The LLZTO band at ~640 and ~740 cm −1 are related with Zr-O bond stretching (Tietz et al, 2013;Larraz et al, 2013) and Ta-O bond stretching (Thompson et al, 2014), respectively. Therefore, the LLZNO band at ~640 and ~720 cm −1 of LLZNO can be assigned to the stretching of ZrO6 and NbO6 octahedron, respectively.…”

Section: Characterization After Cyclingsupporting

confidence: 86%

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

et al. 2016

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The electrochemical stability of Li6.5La3Zr1.5Nb0.5O12 (LLZNO) and Li6.5La3Zr1.5Ta0.5O12 (LLZTO) against metallic Li was studied using direct current (DC) and electrochemical impedance spectroscopy (EIS). Dense polycrystalline LLZNO (ρ = 97%) and LLZTO (ρ = 92%) were made using sol-gel synthesis and rapid induction hot-pressing at 1100°C and 15.8 MPa. During DC cycling tests at room temperature (± 0.01 mA/cm 2 for 36 cycles), LLZNO exhibited an increase in Li-LLZNO interface resistance and eventually short-circuiting while the LLZTO was stable. After DC cycling, LLZNO appeared severely discolored while the LLZTO did not change in appearance. We believe the increase in Li-LLZNO interfacial resistance and discoloration are due to reduction of Nb 5+ to Nb 4+ . The negligible change in interfacial resistance and no color change in LLZTO suggest that Ta 5+ may be more stable against reduction than Nb 5+ in cubic garnet versus Li during cycling.

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Section: Characterization After Cyclingsupporting

confidence: 86%

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

et al. 2016

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“…Figure 6 shows that the spectrograph matches that of cubic garnet regardless of excess lithium amount. 29,30 However, it is also apparent that all samples show some amount of Li 2 CO 3 formation on the surface, as evidenced by the strong peak at 1090 cm −1 . However, the expected carbonate peak (2θ ∼ 31.…”

Section: Resultsmentioning

confidence: 90%

Effect of Excess Li on the Structural and Electrical Properties of Garnet-Type Li₆La₃Ta_1.5Y_0.5O₁₂

Narayanan

Hitz

Wachsman

et al. 2015

J. Electrochem. Soc.

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Volatility of lithium during preparation of lithium-stuffed garnet-type metal oxide solid Li ion electrolytes is a common problem, which affects phase formation, ionic conductivity, mechanical strength and density. Synthesis of Li-stuffed garnets has been performed generally using the conventional solid-state reactions at elevated temperature in air. The present study describes the effect of excess LiNO 3 (2.5 to 15 wt.%) addition during the ceramic synthesis on the structural and electrical properties of garnet-type Li 6 La 3 Ta 1.5 Y 0.5 O 12 . Powder X-ray diffraction (PXRD) confirmed that cubic phase was formed in all tested cases, and there is no significant variation in lattice parameter with amount of excess LiNO 3 used. However, increasing amounts of excess lithium decreased inter-particle contact and increased grain growth during sintering, producing sharply varied microstructures. PXRD showed no secondary phase and scanning electron microscopy (SEM) analysis showed rather uniform morphology and absence of "glassy" materials at the grain-boundaries. The bulk Li ion conductivity was found to increase with amount of excess lithium, reaching a maximum room temperature conductivity of 1.62 × 10 −4 Scm −1 for the sample prepared using 10 wt.% excess LiNO 3 . Raman microscopy study indicated the presence of Li 2 CO 3 in all aged Li 6 La 3 Ta Li-stuffed garnet-type metal oxides have been considered as a potential candidate solid electrolyte material to replace conventional organic liquid based Li ion conducting electrolytes in Li-ion batteries, since members of garnet solid electrolytes exhibit high bulk ion conductivity of 10 −4 -10 −3 Scm −1 at room temperature. Furthermore, some of the garnet-type electrolytes show excellent chemical stability against reaction with elemental Li, Li-ion insertion or intercalation cathodes and high electrochemical stability window.1,2 However, the synthesis of high bulk Li ion conducting garnet-type metal oxidebased lithium ion conductors is a challenging process, very sensitive to preparation conditions used, that are not yet fully characterized. For example, Li 7 La 3 Zr 2 O 12 calcined at 1230• C results in highly conducting (7 × 10 −4 Scm −1 at room temperature) cubic phase with a space group Ia-3d whereas a calcining temperature of 980• C leads to tetragonal phase with a space group I4 1 /acd, which showed 2 orders of magnitude less conductive than cubic phase.3,4 Traditional solid-state techniques are the most commonly used to synthesize garnet-type metal oxides, but usually require the highest sintering temperature resulting in the production of large particles. [5][6][7][8] It is known that volatilization of lithium occurs in the furnace, therefore, several researchers commonly compensate with a 10 wt.% excess lithium precursors.3,9,10 Al-doped Li 7 La 3 Zr 2 O 12 prepared without adding any excess lithium salts during synthesis, but varying the processing using powder cover condition for sintering, greatly affects the morphology, grain size and density. 11Attempts h...

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“…The elemental composition of the Li 7-3x Ga x La 3 Zr 2 O 12 samples obtained by ICP-OES (Table 1) The Raman spectra of tetragonal and cubic garnets are readily distinguishable 37,38 .…”

Section: Composition and Structurementioning

confidence: 99%

“…1 where sharp and split peaks arising from the reduction of symmetry from cubic to tetragonal exist 37,38 . Therefore, samples with x = 0.10 and 0.15 contain both tetragonal and cubic phases, and increasing Ga content to x ≥ 0.20 results in the pure cubic garnet.…”

Section: Composition and Structurementioning

confidence: 99%

Gallium-Doped Li₇La₃Zr₂O₁₂ Garnet-Type Electrolytes with High Lithium-Ion Conductivity

Chen

et al. 2017

ACS Appl. Mater. Interfaces

299

217

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Owing to their high conductivity, crystalline Li 7-3x Ga x La 3 Zr 2 O 12 garnets are promising electrolytes for allsolid-state lithium-ion batteries. Herein, the influence of Ga doping on the phase, lithium-ion distribution, and conductivity of Li 7-3x Ga x La 3 Zr 2 O 12 garnets is investigated, with the determined concentration and mobility of lithium ions shedding light on the origin of the high conductivity of Li 7-3x Ga x La 3 Zr 2 O 12 . When the Ga concentration exceeds 0.20 Ga per formula unit, the garnet-type material is found to assume a cubic structure, but lower Ga concentrations result in the coexistence of cubic and tetragonal phases. Most lithium within Li 7-3x Ga x La 3 Zr 2 O 12 is found to reside at the octahedral 96h site, away from the central octahedral 48g site, while the remaining lithium resides at the tetrahedral 24d site. Such kind of lithium distribution leads to high lithium-ion mobility, which is the origin of the high conductivity; the highest lithium-ion conductivity of 1.46 mS/cm at 25 °C is found to be achieved for Li 7-3x Ga x La 3 Zr 2 O 12 at x = 0.25. Additionally, there are two lithium-ion migration pathways in the Li 7-3x Ga x La 3 Zr 2 O 12 garnets: 96h-96h and 24d-96h-24d, but the lithium ions transporting through the 96h-96h pathway determine the overall conductivity. Disciplines Engineering | Physical Sciences and Mathematics

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Synthesis and Raman micro-spectroscopy investigation of Li7La3Zr2O12

Cited by 141 publications

References 15 publications

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Effect of Excess Li on the Structural and Electrical Properties of Garnet-Type Li₆La₃Ta_1.5Y_0.5O₁₂

Gallium-Doped Li₇La₃Zr₂O₁₂ Garnet-Type Electrolytes with High Lithium-Ion Conductivity

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Synthesis and Raman micro-spectroscopy investigation of Li7La3Zr2O12

Cited by 141 publications

References 15 publications

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Electrochemical Stability of Li6.5La3Zr1.5M0.5O12 (M = Nb or Ta) against Metallic Lithium

Effect of Excess Li on the Structural and Electrical Properties of Garnet-Type Li6La3Ta1.5Y0.5O12

Gallium-Doped Li7La3Zr2O12 Garnet-Type Electrolytes with High Lithium-Ion Conductivity

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Product

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Effect of Excess Li on the Structural and Electrical Properties of Garnet-Type Li₆La₃Ta_1.5Y_0.5O₁₂

Gallium-Doped Li₇La₃Zr₂O₁₂ Garnet-Type Electrolytes with High Lithium-Ion Conductivity