Lowering the sintering temperature of Li7La3Zr2O12 electrolyte for co-fired all-solid-state batteries via partial Bi substitution and precise control of compositional deviation

Ken Watanabe; Ayumu Tashiro; Yoshihiro Ichinose; Shinichi Takeno; Koichi Suematsu; Kazutaka Mitsuishi; Kengo Shimanoe

doi:10.2109/jcersj2.21183

Feature: Cutting edge research on electroceramics, 2021: Full papers

Lowering the sintering temperature of Li₇La₃Zr₂O₁₂ electrolyte for co-fired all-solid-state batteries via partial Bi substitution and precise control of compositional deviation

Ken Watanabe, Ayumu Tashiro, Yoshihiro Ichinose, Shinichi Takeno, Koichi Suematsu, Kazutaka Mitsuishi, Kengo Shimanoe

Author information

Ken Watanabe
Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University
Ayumu Tashiro
Department of Molecular and Material Science, Interdisciplinary Graduate School of Engineering Science, Kyushu University
Yoshihiro Ichinose
Department of Molecular and Material Science, Interdisciplinary Graduate School of Engineering Science, Kyushu University
Shinichi Takeno
Department of Molecular and Material Science, Interdisciplinary Graduate School of Engineering Science, Kyushu University
Koichi Suematsu
Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University
Kazutaka Mitsuishi
Research Center for Advanced Measurement and Characterization, National Institute for Materials Science
Kengo Shimanoe
Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University

Keywords: All-solid-state battery, Garnet-type electrolyte, Liquid-phase sintering, Co-fired battery, Low-temperature sintering

JOURNAL FREE ACCESS

2022 Volume 130 Issue 7 Pages 416-423

DOI https://doi.org/10.2109/jcersj2.21183

Details

Abstract

Li₇La₃Zr₂O₁₂ (LLZ) has great potential as a solid electrolyte for co-fired all-solid-state Li-ion secondary batteries. However, to realise a solid-state battery using LLZ, the sintering temperature of LLZ should be reduced to one that can suppress the formation of a high-resistance reaction layer at the interface between LLZ and the electrode. In this study, we demonstrate an effective method for reducing the sintering temperature of Li₆La₃ZrTaO₁₂ by combining partial Bi-substitution for Ta and precise control of the compositional deviation. The intentional tuning of the La deficiency in Li₆La₃ZrTa_0.8Bi_0.2O₁₂ (LLZTB0.2) promoted the formation of a liquid phase based on Li₂O–Bi₂O₃ at the grain boundary, resulting in its densification at 775 °C. Furthermore, we fabricated a co-fired all-solid-state half-cell based on an LLZTB0.2 electrolyte attached to a LiCoO₂ + LLZTB0.2 composite electrode and a half-cell operated at 60 °C. From these results, it was found that the proposed concept is effective in reducing the sintering temperature of LLZ and is applicable for co-firing an all-solid-state battery.

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