Osaka Prefecture University

Our Research Group has Developed a New Technique to Evaluate the Thermal Stability of Electrode Materials for All-Solid-State Lithium Batteries

LastUpDate: April 18, 2018

Dr. Hirofumi TSUKASAKI, Prof. Shigeo MORI, Prof. Akitoshi HAYASHI, and Prof. Masahiro TATSUMISAGO from the Osaka Prefecture University, Dr. Yoshinori TANAKA and Dr. Takahisa OHNO from the National Institute for Materials Science, together with other collaborators have developed a new technique to evaluate the thermal stability of electrode materials that are expected to be applicable for all-solid-state lithium batteries. This work is supported by the Japan Science & Technology Agency Strategic Basic Research Programs and the Advanced Low Carbon Technology Research and Development Program of Specially Promoted Research for Innovative Next Generation Batteries (ALCA-SPRING). This new technique could provide a step forward toward clarifying the mechanism of the exothermal reaction that occurs in electrode materials.


  1. Our study revealed, via in situ transmission electron microscopy (TEM) observation during heating(*1), that the exothermic reaction occurring at positive electrode composites in all-solid-state lithium batteries was due to the crystallization of inorganic solid electrolytes.
  2. The exothermic reaction at the positive electrode composite was found to be derived from the heat generated by the decomposition reaction of the inorganic solid electrolyte, which was induced by the interfacial contact between solid electrolytes and electrode active materials.
  3. The results of the present study significantly contribute to the development and realization of next-generation all-solid-state lithium batteries.


Recently, large-sized lithium-ion secondary batteries with higher energy density have become extremely promising candidates for their application in electric vehicles, hybrid electric vehicles, and accumulators for household use. To realize this practical use, ensuring safety by suppressing heat generation and preventing thermal runaway is crucial. Moreover, heat generation degrades battery life. Therefore, examining the exothermic behavior of battery materials and clarifying the origin of the exothermic reaction are necessary.

In this study, the thermal stability of positive electrode layers comprising LiNi1/3Mn1/3Co1/3O2 (NMC) and 75Li2S∙25P2S5 (LPS) glass electrolytes have been investigated via in situ TEM observation during heating. Furthermore, based on the in situ TEM observations and first-principle calculation(*2), we have examined the chemical reaction occurring at the interface between NMC and LPS, as well as the origin of the exothermal reaction.

The results of this study were published in “Scientific Reports”, a part of the Nature Publishing Group on April 18, 2018 (Japan time).

Article Title: Crystallization behavior of the Li2S–P2S5 glass electrolyte in the LiNi1/3Mn1/3Co1/3O2 positive electrode layer


*1 In situ observation during heating

In situ observation refers to direct TEM observation of the microstructure, phase transition, and crystallization process of a sample. The heating TEM holder used in this study can both prevent the samples’ exposure to air and control the temperature in real time, thereby enabling direct investigation of the electrode composites’ structural changes during heating.

*2 First-principle calculation

First principle calculation is a method to calculate the electronic state and energy of a material without empirical parameters in terms of quantum mechanics. As the change of the electronic state is calculated, we can precisely analyze the chemical reaction, in which the recombination of bonding between atoms occurs.


Department of Materials Science, Graduate School of Engineering

Dr. Hirofumi TSUKASAKI

E-mail h-tsukasaki57[at] *Please change [at] to @.

Prof. Shigeo MORI

E-mail mori[at] *Please change [at] to @.