Osaka Prefecture University

A Research Group Has Clarified a Heat Generation Mechanism of Cathode Materials for a Liquid Electrolyte-Based Lithium Batteries

LastUpDate: October 26, 2018

Project Assistant Prof. Hirofumi Tsukasaki, Prof. Shigeo Mori, Prof. Akitoshi Hayashi and Prof. Masahiro Tatsumisago from the Osaka Prefecture University (Chief Director: Hiroshi Tsuji), Associate Prof. Hideyuki Morimoto from the Gunma University (Chief Director: Hiroshi Hiratsuka), together with other collaborators have developed a novel technique to evaluate the thermal stability of electrode materials for a liquid electrolyte-based lithium batteries. This work is supported by the Japan Science & Technology Agency (JST, Chief Director: Michinari Hamaguchi) 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 typical lithium batteries comprising of organic solvent and electrode materials.

The main point of research

  1. figureThe study revealed, via ex situ transmission electron microscopy (TEM) observation, that the decomposition reaction of electrolytes was directly involved in the exothermic reaction exhibited by cathode composites.
  2. It was found that the oxidation reaction between the released O2 gas from cathode active materials and the organic solvents was also likely involved in the exothermic reaction.
  3. The results of the present study significantly contribute to the development and realization of next-generation lithium batteries.


Large-sized lithium-ion secondary batteries with high energy density(*1) are currently expected to be applied to electric vehicles and hybrid electric vehicles. However, because flammable organic solvents are used in liquid electrolytes, there are serious safety concerns such as the possibility of thermal runaway. To realize practical large-sized lithium-ion batteries with higher energy density, ensuring safety by suppressing heat generation and preventing thermal runaway is crucial. It is therefore necessary to evaluate the exothermic behavior of battery materials and identify the origin of the exothermic reaction.

This study investigated the exothermal behavior and its main factor of cathode composites for liquid electrolyte-based cells using ex situ TEM observation. In this study, LiNi1/3Mn1/3Co1/3O2 was used as a cathode material, while ethylene carbonate and ethyl methyl carbonate, in which the lithium hexafluorophosphate salt (LiPF6) is dissolved, were used as an organic solvent.

The results of this study were published online in “Scientific Reports,” a part of the Nature Publishing Group on October 23, 2018 (Japan time).


*1 High energy density

The amount of energy per unit mass or volume that can be extracted from the battery.


Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University
Dr. Hirofumi Tsukasaki (Project Assistant Professor)

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

Prof. Shigeo Mori

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