Low temperature synthesis of highly ion conductive Li7La3Zr2O12–Li3BO3 composites

Tadanaga, Kiyoharu; Takano, Ryohei; Ichinose, Takahiro; Mori, Shigeo; Hayashi, Akitoshi; Tatsumisago, Masahiro

doi:10.1016/j.elecom.2013.04.004

Cited by 119 publications

(82 citation statements)

References 14 publications

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“…11 Attempts have also been made to reduce the sintering temperature and improve the control of stoichiometry via wet chemical synthesis as well as through additives acting as sintering aids. [12][13][14][15][16][17][18] It has been shown that Al migrates from the alumina crucible used for garnet synthesis, causing significant effects in the material including stabilization of the cubic phase. [15][16][17][18] Lithium salts such as Li 2 20 They also found that the glassy-like phase formed at the grain-boundaries increases the density of material as well as helps to decrease the grain-boundary and improve the total Li + conductivity.…”

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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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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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“…On the other hand, the reduction of Li3BO3 content leads to the decrease, circa of 10%, of relative density. Higher content of Li3BO3 could create an unfavorable effect producing the drop of the Li-ion conductivity since the Li-ion 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 8 conductivity of Li3BO3 is two orders of magnitude lower than that of the LLZ garnet [15,18] [18,14].…”

Section: Resultsmentioning

confidence: 99%

“…Combination of Al and Li3BO3 has been reported to be particularly useful to produce denser material at lower sintering temperatures [14,15]. Li-ion conductivity of LLZ sintered at 900 °C (36 h) with 0.3 moles of Al and 0.68 moles of Li3BO3 [14] achieves 1 × 10 -4 S/cm.…”

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“…Li-ion conductivity of LLZ sintered at 900 °C (36 h) with 0.3 moles of Al and 0.68 moles of Li3BO3 [14] achieves 1 × 10 -4 S/cm. High Li-ion conductivity at lower sintering temperatures has been attained using sintering additives in materials with aliovalent substitution of LLZ garnet structure.…”

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“…Li-ion conductivity of Li6.625La3Zr1.625Ta0.375O12 sintered at 1000 °C (24 h) with 29 mol% Al [12] reaches 5 × 10 -4 S/cm. Other compounds used as sintering additives include Li2O, Li3BO3, Li3PO4 and Li4SiO4 [13][14][15][16][17][18]. These materials act as binder between the garnet particles during the sintering treatment by the formation of liquid phases at low temperatures, reducing the grain boundary resistance and improving the Li-ion conductivity pathway.…”

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Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7−x La2.95Ca0.05ZrTaO12 at Low Temperature

Rosero-Navarro

Miura

Higuchi

et al. 2016

Journal of Elec Materi

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Simultaneous effect of Al2O3 and Li3BO3 addition on sintering behavior and Li-ion conductivity of Li7-xLa2.95Ca0.05ZrTaO12 (LLCZT) garnet electrolyte sintered at 900 °C (10 h) is evaluated. Crystal phase and microstructure of the different composites were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrical properties of the composites with high relative densities (95 %) were examined by impedance spectroscopy (EIS). Cubic phase was formed for LLCZT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

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Amorphous Dual‐Layer Coating: Enabling High Li‐Ion Conductivity of Non‐Sintered Garnet‐Type Solid Electrolyte

Gao

Sun

Zhang

et al. 2021

Adv Funct Materials

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Garnet‐type oxide Li6.4La3Zr1.4Ta0.6O12 (LLZTO) has attracted considerable attention as a highly promising solid state electrolyte. However, its high ionic conductivity is achievable only after high temperature sintering (≈1200 °C) to form dense pellets but with detrimental brittleness and poor contact with electrodes. Herein, a novel strategy to achieve high Li+ ion conductivity of LLZTO without sintering is demonstrated. This is realized by ball milling LLZTO together with LiBH4, which results in a LLZTO composite with unique amorphous dual coating: LiBO2 as the inner layer and LiBH4 as the outer layer. After cold pressing the LLZTO composite powders under 300 MPa to form electrolyte pellets, a high Li+ ion conductivity of 8.02 × 10–5 S cm–1 is obtained at 30 °C, which is four orders of magnitude higher than that of the non‐sintered pristine LLZTO pellets (4.17 × 10–9 S cm–1). The composite electrolyte displays an ultrahigh Li+ transference number of 0.9999 and enables symmetric Li–Li cells to be cycled for 1000 h at 60 °C and 300 h at 30 °C. The significant improvements are attributed to the continuous ionic conductive network among LLZTO particles facilitated by LiBH4 that is chemically compatible and electrochemically stable with Li metal electrode.

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Low temperature synthesis of highly ion conductive Li7La3Zr2O12–Li3BO3 composites

Cited by 119 publications

References 14 publications

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

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

Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7−x La2.95Ca0.05ZrTaO12 at Low Temperature

Amorphous Dual‐Layer Coating: Enabling High Li‐Ion Conductivity of Non‐Sintered Garnet‐Type Solid Electrolyte

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Low temperature synthesis of highly ion conductive Li7La3Zr2O12–Li3BO3 composites

Cited by 119 publications

References 14 publications

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

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

Optimization of Al2O3 and Li3BO3 Content as Sintering Additives of Li7−x La2.95Ca0.05ZrTaO12 at Low Temperature

Amorphous Dual‐Layer Coating: Enabling High Li‐Ion Conductivity of Non‐Sintered Garnet‐Type Solid Electrolyte

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

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