Interface and interphase: exploration of ion dynamics in solid-state composite electrodes

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14720
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 36020:Energy-related chemistry
• Research Institution: Kyushu University
• Principal Investigator: Ohno Saneyuki 九州大学, 工学研究院, 助教 (30892533)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 全固体電池 / イオン輸送 / 電気化学 / リチウム硫黄電池 / 複合電極

Outline of Final Research Achievements

The electrodes for batteries are multi-component composites in which the components come together and form interfaces. During battery operation varying voltage is applied, and various phenomena occur in the vicinity of the interface, and understanding these phenomena is essential for high-performance and long-lifetime solid-state batteries. This research focused primarily on interface and interphases. It is known that the solid electrolytes decompose and form interphases, and the effective ion transport of composites changes when a voltage outside of the electrochemical stability window of electrolytes is applied. This study established a method to quantitatively measure the effective ionic conductivity of the composite with various applied voltages. As a spin-off of the project, a method to suppress the intrinsic variation of ionic conductivity in solid electrolytes was theoretically established and experimentally demonstrated by utilizing fundamental thermodynamics.

Free Research Field

エネルギー化学

Academic Significance and Societal Importance of the Research Achievements

全固体電池向け硫黄正極内のキャリア輸送測定の基盤を構築した。とくに複合体内部でのイオン輸送の計測をインピーダンス測定とその解析を用いて計測する手法が確立できたことは、電位依存の輸送変化の計測を初めて可能にした。これにより複合体の定量的な輸送解析ができるようになった。また、固体電解質が持つイオン伝導度のばらつきを低減する熱力学的な手法も提案した。固体電解質に微量の共存相をあえて混入させることで系の熱力学的な状態を規定し、固体電解質中の欠陥量を安定させることでこれを可能にした。これらの成果は全固体電池研究一般に有用な成果である。