300度で世界最高のプロトン伝導率を有する安定酸化物を開発～大型トラックなど固体酸化物形燃料電池の多用途化を推進～

2025-08-08 九州大学

図１．プロトン伝導率の温度依存性

＜関連情報＞

• https://www.kyushu-u.ac.jp/ja/researches/view/1299/
• https://www.kyushu-u.ac.jp/f/62816/25_0808_04.pdf
• https://www.nature.com/articles/s41563-025-02311-w

立方晶ペロブスカイト酸化物におけるプロトン捕獲の軽減にScO6八面体ネットワークを活用Mitigating proton trapping in cubic perovskite oxides via ScO6 octahedral networks

Kota Tsujikawa,Junji Hyodo,Susumu Fujii,Kazuki Takahashi,Yuto Tomita,Nai Shi,Yasukazu Murakami,Shusuke Kasamatsu & Yoshihiro Yamazaki
Nature Materials  Published:08 August 2025
DOI:https://doi.org/10.1038/s41563-025-02311-w

Abstract

Advances in electrochemical devices have been primarily driven by the discovery and development of electrolyte materials. Yet the development of high-performance and chemically stable proton-conducting oxide electrolytes remains a challenge due to proton trapping and the resulting trade-offs between ionic carrier concentration and conductivity in doped oxides. Here we demonstrate that cubic perovskite oxides with heavy Sc doping can overcome these limitations. BaSn_0.3Sc_0.7O_3–δ and BaTi_0.2Sc_0.8O_3–δ are found to exceed the technological threshold of a total proton conductivity of 0.01 S cm⁻¹ for fuel cell electrolytes at 300 °C. The structural stability of BaSn_0.3Sc_0.7O_3–δ is further validated under harsh chemical and fuel cell conditions. Molecular dynamics simulations using a machine learning force field illustrate rapid proton diffusion pathways along the ScO₆ octahedral network, effectively mitigating proton trapping, while protons are preferentially associated with Sc. Lattice softness is proposed as a primary design descriptor for increasing Sc content in perovskite oxides and developing high-performance electrolytes for electrochemical devices.