Development of methods for lithium self-diffusion coefficient measurements in mixed conductors using isotope exchange

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H03872
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Inorganic industrial materials
• Research Institution: Tohoku University
• Principal Investigator: Kuwata Naoaki 東北大学, 多元物質科学研究所, 准教授 (00396459)
• Co-Investigator(Renkei-kenkyūsha): KAWAMURA JUNICHI 東北大学, 多元物質科学研究所, 教授 (50142683) ; MIYAZAKI TAKAMICHI 東北大学, 工学研究科, 技術職員 (20422090)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 混合伝導体 / 拡散係数 / 空孔拡散機構 / LiCoO2 / LiMn2O4 / 二次イオン質量分析 / 全固体電池 / インターカレーション

Outline of Final Research Achievements

Lithium-ion battery electrode materials are mixed conductors which have significant conduction of both ionic and electronic. It is proved that a measurement of lithium diffusion coefficient in the mixed conductors is difficult, and the method for the diffusion measurement has not been established. The aim of this study is to develop the method to measure the tracer diffusion coefficient of the mixed conductors by using secondary ion mass spectrometry (SIMS), based on the idea that 6Li in the cathode material can be replaced with 7Li by electrochemical charge-discharge. As a result of this study, we succeeded to develop three kinds of ion-exchange methods and to clarify the diffusion coefficient of thin films a-Li3PO4, LiMn2O4 and LiCoO2 by using the developed methods. It has been found that the temperature and composition dependence of the diffusion coefficients in the intercalation electrodes are able to explain by vacancy diffusion mechanism.

Free Research Field

固体イオニクス