Journal Article FZJ-2024-02787

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The effects of aluminum concentration on the microstructural and electrochemical properties of lithium lanthanum zirconium oxide

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2022
RSC London ˜[u.a.]œ

Journal of materials chemistry / A 10(41), 21955 - 21972 () [10.1039/D2TA03676B]

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Abstract: Cubic lithium lanthanum zirconium oxide (Li7−xAlxLa3Zr2O12, LLZO) garnet has gained attention as a promising next-generation electrolyte for lithium batteries due to its high ionic conductivity and chemical stability with lithium metal. The high conductivity can be achieved through doping over a range of aluminum concentrations. In this study, we hot-pressed samples to achieve <2% nominal porosity with aluminum concentrations from x = 0.25–0.55 mol to understand the effect of aluminum on microstructure and electrochemistry. It was observed that beyond the aluminum solubility limit (x = ∼0.40), resistive secondary phases formed at the grain boundaries. As a result, the percent grain boundary resistance increased from 17.6 to 41.2% for x = 0.25 and x = 0.55, respectively. Both the grain boundary and bulk activation energies remained relatively constant as the aluminum concentrations increased (∼0.44 eV and ∼0.39 eV, respectively). It was, therefore, surmised that the mobility term of the Nernst–Einstein equation was roughly independent of aluminum concentration and the major variable controlling bulk conductivity was the number of lithium charge carriers. As a result, as the aluminum concentration increased from x = 0.25 to x = 0.55 the bulk conductivity decreased from 0.56 to 0.15 mS cm−1. Following these trends of increasing grain boundary resistance and decreasing bulk conductivity with increasing aluminum concentration, x = 0.25 had the highest total conductivity (0.46 mS cm−1). We demonstrated that aluminum concentration has a significant effect on the microstructure and electrochemical properties of LLZO. We believe this work could help understand how to link processing, microstructure, and electrochemical properties to guide the manufacturing of LLZO for use in solid-state batteries.

Classification:

Contributing Institute(s):
  1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)
Research Program(s):
  1. 1221 - Fundamentals and Materials (POF4-122) (POF4-122)
  2. 1222 - Components and Cells (POF4-122) (POF4-122)

Database coverage:
Medline ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 10 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection
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 Record created 2024-04-15, last modified 2024-07-08



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