室温かつ短時間で、リチウム金属とガーネット型酸化物固体電解質の界面形成に成功 ―全固体電池の実用化を後押しする新しい手法―

2026-03-24 東北大学

図1. 室温で数秒間の超音波接合により形成された、リチウムと固体電解質の界面断面像

＜関連情報＞

• https://www.tohoku.ac.jp/japanese/2026/03/press20260324-02-Lithium.html
• https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20260324_02web_Lithium.pdf
• https://onlinelibrary.wiley.com/doi/10.1002/sstr.202500866

ガーネット固体電解質とリチウム金属の超音波溶接：数秒で密着した界面接触を実現 Ultrasonic Welding of Garnet Solid Electrolytes to Lithium Metal: Achieving Intimate Interfacial Contact in Seconds

Mikihisa Fukuda, Ying Li, Run-Zi Wang, Shin-ichi Orimo, Yutaka S. Sato, Hidemi Kato, Eric Jianfeng Cheng
Small Structures  Published: 19 March 2026
DOI:https://doi.org/10.1002/sstr.202500866

Abstract

Solid-state batteries (SSBs) are widely regarded as promising next-generation energy storage technology due to their potential for enhanced safety and higher energy density compared to conventional Li-ion batteries. Among the various oxide solid electrolytes, garnet Li₇La₃Zr₂O₁₂ (LLZO) is considered one of the most promising, yet the Li–LLZO solid–solid interface remains a major bottleneck. Both LLZO and the relatively stiff Li metal anode rapidly accumulate Li₂CO₃ surface impurities and form limited contact, leading to large interfacial resistance. Here, we demonstrate that ultrasonic welding (USW) provides a rapid, mechanically driven route to establish intimate Li–LLZO contact within seconds. A preliminary ambient-air experiment confirms the basic feasibility of the technique, while all controlled welding experiments performed in Ar yield Li/LLZO interfaces with resistances on the order of several hundred Ω cm². Systematic comparison of pyramidal and flat horn geometries reveals that uniform pressure delivery is essential for stable interfacial formation, with the flat horn reducing the resistance to approximately 225 Ω cm². Furthermore, introducing a sputtered Au interlayer significantly enhances mechanical conformity and wetting by compensating LLZO surface roughness and enabling Li to more effectively accommodate LLZO surface asperities. As a result, the interfacial resistance decreases to as low as 1.5 Ω cm², among the lowest values reported for garnet–Li interfaces processed at room temperature. This study demonstrates USW as an effective mechanical strategy for constructing low-resistance Li–garnet interfaces suitable for next-generation SSBs.