Development of material conversion devices utilizing hydrogen charge flexibility

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K18909
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: KOBAYASHI Genki 国立研究開発法人理化学研究所, 開拓研究本部, 主任研究員 (30609847)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: ヒドリドイオン導電体 / 電気化学 / 固体イオニクス / 水素

Outline of Final Research Achievements

Elemental substitution into Ba1.75LiH2.7O0.9 (BLHO), which shows H- superionic conductivity via a phase transition at 300 °C, stabilizes the superionic conduction state at low temperatures and enables the formation of an electrode/electrolyte interface. The sintering process of BLHO-based hydride ion conductors was also investigated, and the relative density was successfully increased to 98%, enabling solid electrolyte applications at 300 - 350 ℃.
Electrochemical devices using the BLHO-based solid electrolyte were fabricated and found to be able to convert nitrogen to ammonia by an electrochemical reaction at a rate exceeding the theoretical conversion efficiency at 350 ℃ and 1 atm.

Free Research Field

無機固体化学、固体イオニクス

Academic Significance and Societal Importance of the Research Achievements

ヒドリドイオン導電体の導電率向上のみならず、焼結などの固体電解質応用につながる要素技術開発に取り組んでデバイス化を実現したことは、ヒドリドの還元力を活用した新たな電気化学応用の創出に直結する成果であり、ヒドリドのイオニクス研究を新たなステージに押し上げたといえる。また、デバイス化によって実現した高効率な窒素-アンモニア転換反応は、将来的な水素エネルギー利用の基盤になり得る成果であり、社会的な意義も大きい。