Invention of next-generation secondary battery materials using dual redox-active organic molecules

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02690
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: Ehime University
• Principal Investigator: Misaki Yohji 愛媛大学, 理工学研究科(工学系), 教授 (90202340)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 有機電池材料 / 正極活物質 / ドナー・アクセプター分子系 / テトラチアフルバレン / ベンゾキノン / 充放電 / 二次電池

Outline of Final Research Achievements

Fused donor-acceptor molecular systems composed of electron-donating tetrathiafulvalene (TTF) and electron-accepting p-benzoquinone (BQ) were developed to achieve higher capacity, improved cycle characteristics due to lower solubility, and increased active material allocation due to improved conductivity. Among the obtained molecules, the redox behavior of the derivatives with readily soluble substituents in a solution was investigated by cyclic voltammetry. Charge-discharge properties of rechargeable batteries were investigated using the poorly soluble derivatives as positive electrode active materials. It is noted that the discharge capacity and discharge energy density of the rechargeable battery using the unsubstituted derivative of TTF-TTF-BQ fused triad molecules were improved to 299 mAh/g and 855 mWh/g, respectively.

Free Research Field

Structural organic chemistry

Academic Significance and Societal Importance of the Research Achievements

本研究における試みは，従来無機物質の独壇場であった電池材料を，電池に不向きと考えられていた有機物質に置き換える，という点でエポックメイキングであり，学術的な意義は大きい。一般的に，有機材料は無機材料に比べ低融点であり，融解に伴う吸熱反応により熱暴走が起こりにくい，という利点がある。安全性の高い「有機二次電池」が，現状のリチウムイオン電池を凌ぐエネルギー密度を持つ高性能二次電池として将来的に実用化されたならば，家庭用，集合住宅用，あるいは分散型発電との組み合わせによるマイクログリッド用など，安全性が重要視される定置型大型電池への展開が期待されるので社会的に意義深い。