Tantalum‐doped lithium lanthanum zirconate garnet (Li7−
- Award ID(s):
- 1553519
- NSF-PAR ID:
- 10251510
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 8
- Issue:
- 34
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 17405 to 17410
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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x La3Zr2−x Tax O12[LLZTO]) has received interest as a solid electrolyte for solid‐state lithium batteries due to its good electrochemical properties and ionic conductivity. However, the source of discrepancies for reported values of ionic conductivity in nominally or nearly equivalent compositions of LLZTO is not completely clear. Herein, synthesis‐related factors that may contribute to the differences in performance of garnet electrolytes are systematically characterized. The conductivity of samples with composition Li6.4La3Zr1.4Ta0.6O12prepared by various methods including solid‐state reaction (SSR), combustion, and molten salt synthesis is compared. Varying levels of elemental inhomogeneity, comprising a variation in Ta and Zr content on the level of individual LLZTO particles, are identified. The elemental inhomogeneity is found to be largely preserved even after high‐temperature sintering and correlated with reduced ionic conductivity. It is shown that the various synthesis and processing‐related variables in each of the preparation methods play a role in these compositional variations, and that even LLZTO synthesized via conventional, high‐temperature SSR can exhibit substantial variability in local composition. However, by improving reagent mixing and using LLZTO powder with low agglomeration and small particle size distribution, the compositional uniformity, and hence, ionic conductivity, of sintered garnet electrolytes can be improved. -
Abstract Efficient and affordable synthesis of Li+functional ceramics is crucial for the scalable production of solid electrolytes for batteries. Li‐garnet Li7La3Zr2O12−d(LLZO), especially its cubic phase (cLLZO), attracts attention due to its high Li+conductivity and wide electrochemical stability window. However, high sintering temperatures raise concerns about the cathode interface stability, production costs, and energy consumption for scalable manufacture. We show an alternative “sinter‐free” route to stabilize cLLZO as films at half of its sinter temperature. Specifically, we establish a time‐temperature‐transformation (TTT) diagram which captures the amorphous‐to‐crystalline LLZO transformation based on crystallization enthalpy analysis and confirm stabilization of thin‐film cLLZO at record low temperatures of 500 °C. Our findings pave the way for low‐temperature processing via TTT diagrams, which can be used for battery cell design targeting reduced carbon footprints in manufacturing.
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Abstract Efficient and affordable synthesis of Li+functional ceramics is crucial for the scalable production of solid electrolytes for batteries. Li‐garnet Li7La3Zr2O12−d(LLZO), especially its cubic phase (cLLZO), attracts attention due to its high Li+conductivity and wide electrochemical stability window. However, high sintering temperatures raise concerns about the cathode interface stability, production costs, and energy consumption for scalable manufacture. We show an alternative “sinter‐free” route to stabilize cLLZO as films at half of its sinter temperature. Specifically, we establish a time‐temperature‐transformation (TTT) diagram which captures the amorphous‐to‐crystalline LLZO transformation based on crystallization enthalpy analysis and confirm stabilization of thin‐film cLLZO at record low temperatures of 500 °C. Our findings pave the way for low‐temperature processing via TTT diagrams, which can be used for battery cell design targeting reduced carbon footprints in manufacturing.
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