Exploration of novel fluoride anion conductors with rigid frameworks

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04659
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Kindai University
• Principal Investigator: Oka Kengo 近畿大学, 理工学部, 講師 (80602044)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: フッ化物イオン伝導体 / 複合アニオン化合物 / 酸フッ化物 / ビスマス / 鉛

Outline of Final Research Achievements

Fluoride anion conductors with rigid frameworks were investigated. We focused mainly on compounds containing Pb and Bi. The oxyfluoride Bi2VO5F has been reported as a fluoride anion conductor. While this material has been conventionally synthesized by solid-phase reactions, we have found that it can be synthesized at low temperatures and in a very short time by a topotactic fluorination reaction based on the oxide Bi4V2O11. We have also experimentally confirmed that this property is due to the high fluoride anion conductivity. For the apatite-type compound Pb5(VO4)3F, it was also found that the fluoride ionic non-stoichiometry exists, and that the fluoride ionic conductivity is expected to derive from this non-stoichiometry.

Free Research Field

固体化学

Academic Significance and Societal Importance of the Research Achievements

本研究では、安定かつ強固な酸化物骨格を持った化合物におけるフッ化物イオン伝導特性に着目して研究を行った。フッ化物イオン伝導体は、新しいフッ化物イオン二次電池に必要な材料として注目を集めている。従来は、フッ化物イオンのみをもつ化合物が正極材料として着目されていたが、フッ化物イオンの脱離吸収過程における化学的安定に問題がった。本研究で見いだしたBi2VO5FおよびPb5(VO4)3Fは、安定な酸素骨格を持ち、フッ素の脱離吸収の繰り返しに関して安定である。PbやBiは6s孤立電子対を安定的に有する元素であり、その特性が安定的なフッ化物イオンの保持に寄与している可能性が期待される。