Creation of novel solid-state ionics exploiting low-temperature sublattice melting accompanied by pseudorotation of hydride complexes

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K20438
• Project/Area Number (Other): 19H05514 (2019)
• Research Category: Grant-in-Aid for Challenging Research (Pioneering)
• Allocation Type: Multi-year Fund (2020); Single-year Grants (2019)
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Tohoku University
• Principal Investigator: Takagi Shigeyuki 東北大学, 金属材料研究所, 准教授 (50409455)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 錯体水素化物 / 擬回転 / 固体イオニクス

Outline of Final Research Achievements

Solid-state materials containing rotatable polyanions constitute a peculiar class of ionic conductors due to their unique transport behavior, where rotating polyanions promote phase transitions to disordered phases with several orders of magnitude enhancement in cation conductivities. A major drawback is the high temperature required to activate rotation and thereby low conductivities at room temperature. In this study, we elucidate a mechanism to drastically reduce the temperature based on the use of pseudorotation in high-H coordination hydride complexes. We theoretically and experimentally demonstrate this mechanism for an existing complex transition metal hydride containing a hydride complex with ninefold H coordination and we find a strong potential of this material to unprecedentedly exhibit a high lithium ion conductivity at room temperature.

Free Research Field

計算材料科学

Academic Significance and Societal Importance of the Research Achievements

本研究では、イオン輸送現象における『水素錯イオンの擬回転』の関与など、従来の固体イオニクスにはない新たな指導原理の獲得につながる重要な知見を得た。本成果により、既存の学術体系の枠組みの中では成し得なかった超機能材料の創製が可能となり、水素化物関連分野の発展のみならず、全固体二次電池関連の広範な学問分野における新たな研究領域開拓に貢献できるものと期待する。