Development of anhydrous organic superprotonic conductors utilizing molecular dynamics

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K15240
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: The University of Tokyo
• Principal Investigator: Dekura Shun 東京大学, 物性研究所, 特任助教 (80837948)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 水素 / 固体電解質 / 無水プロトン伝導体 / 分子性固体 / 分子ダイナミクス

Outline of Final Research Achievements

In this study, to reveal the relationship between molecular motions in solids and anhydrous proton (H+) conductivity, we prepared single-crystalline imidazolium (ImH+) salts and investigated their anhydrous H+ conductivity including anisotropy, as well as the conduction mechanism by evaluating molecular motion. As a result, although the target conductivity of 0.01 S/cm was not achieved, the conduction mechanism due to the rotational motion of ImH+ was clarified in several systems, and the highest conductivity of >0.001 S/cm was realized in a system showing 3D ImH+ rotational motion. On the other hand, in a system in which ImH+ was replaced by 1,2,3-triazolium, low-barrier high conductivity of >0.001 S/cm due to H+ tautomerism were found, indicating the possibility of developing a new conduction mechanism that can replace molecular motion.

Free Research Field

水素機能物性

Academic Significance and Societal Importance of the Research Achievements

高効率な無水有機固体プロトン伝導体は、無加湿で動作可能な次世代型燃料電池の固体電解質への応用が期待されるが、本研究の成果は顕著な分子ダイナミクスがかつてない高プロトン伝導性をもたらすことを示しただけでなく、プロトン互変異性という新たな高伝導性物質の設計指針を提示しており、実用的な固体電解質の設計指針に大きく貢献する結果である。一方、無水有機結晶中のプロトン輸送現象は、量子波動性を伴うプロトンの水素結合中移動・分子運動・プロトン脱着に伴う電子系の組み替えが協奏した基礎研究的にも重要な課題であり、本研究の成果は環境科学・材料科学のみならず物性科学などの周辺分野への波及効果が大きいと考えられる。