パイロクロア型酸化物系固体電解質で有機電解液レベルのイオン伝導率を達成 －安全性の高い酸化物系全固体電池の実現に向けた技術開発が進展－

2026-03-11 産業技術総合研究所

＜関連情報＞

• https://www.aist.go.jp/aist_j/press_release/pr2026/pr20260311/pr20260311.html
• https://pubs.acs.org/doi/10.1021/acsmaterialslett.5c01541

放電プラズマ焼結法によるパイロクロア型Li 1.25La0.58Nb2O6F固体電解質の合成 Synthesis of Pyrochlore-type Li1.25La0.58Nb2O6F Solid Electrolyte via Spark Plasma Sintering

Yushi Fujita,Tomonari Takeuchi,Yuta Ito,Toyoki Okumura
ACS Materials Letters  Published March 11, 2026
DOI:https://doi.org/10.1021/acsmaterialslett.5c01541

Abstract

Oxide-based lithium-ion conductors are attractive due to their chemical stability. Among these, pyrochlore-type oxyfluorides have emerged as a solid electrolyte family with high ionic conductivity and strong water tolerance. However, their ionic conductivity remains lower than those of previously reported sulfide- and oxychloride-based solid electrolytes. In addition, sintered pellets exhibit poor densification, limiting lithium-ion transport. In this study, spark plasma sintering (SPS) was employed to prepare and densify pyrochlore-type Li_1.25La_0.58Nb₂O₆F solid electrolytes. SPS enables rapid synthesis within minutes compared to conventional solid-state synthesis and yields dense pellets with a relative density of 98%. Owing to the reduction of grain boundary resistance, the SPS-processed samples exhibited the highest bulk conductivity (15 mS cm^–1 at 300 K) reported to date for oxide-based lithium-ion conductors. This study is significant in the development of oxide-based solid electrolytes, opening opportunities in a field long dominated by sulfide-, chloride-, and oxychloride-based systems.