2022 Fiscal Year Final Research Report

In-situ analysis of thermal decomposition of electrode materials during thermal runaway of lithium-ion batteries

Research Project

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Project/Area Number	19K04941
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 25020:Safety engineering-related
Research Institution	National Institute of Advanced Industrial Science and Technology
Principal Investigator	Saito Yoshiyasu 国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 主任研究員 (10357064)
Co-Investigator(Kenkyū-buntansha)	小林弘典国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 総括研究主幹 (30357016) 岡田賢国立研究開発法人産業技術総合研究所, エネルギー・環境領域, 主任研究員 (80356683)
Project Period (FY)	2019-04-01 – 2023-03-31
Keywords	リチウムイオン電池 / 熱暴走 / 非破壊分析 / X線回折測定
Outline of Final Research Achievements	We developed a heating system for x-ray diffraction measurement using high energy x-ray with high transparency in a synchrotron radiation facility、SPring-8, by which crystal structure of electrode materials included in lithium-ion batteries can be characterized without destruction. In the system, open circuit voltage of the sample batteries and inner pressure of the sample holder which was related to gas quantity were also could be measured simultaneously. By using this system, we clarified temperature region where lithium de-intercalation reaction occured at the graphite anode in a real battery which was related to capacity degradation during storage. In addition, crystal structure change of thermal decomposition reaction of the nickel-based oxide cathode material was ascertained at elevated temperature which was related to thermal runaway of the battery.
Free Research Field	電気化学
Academic Significance and Societal Importance of the Research Achievements	リチウムイオン電池の構成材料の熱暴走反応の解明のために、従来は電池を解体して正極や負極を抽出し、材料ごとに評価が行われていたが、解体時の試料の変質や、正極と負極の相互作用について評価できないという課題があった。本研究では、電池を解体せずにそのまま試料として用いる評価法を確立し、この問題を解決した。本手法を活用し、更に熱測定や発生ガス分析等と組み合わせて総合的な評価を行うことで、高温の電池内で生じる種々の反応のメカニズムが明らかになる。更には、電池の寿命や安全性の予測が可能になるとともに、長寿命化や高安全化のために方策検討にも貢献できる。