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Title
Japanese: 
English:Phase transition kinetics of LiNi0.5Mn1.5O4 analyzed by temperature-controlled operando X-ray absorption spectroscopy 
Author
Japanese: Ikuma Takahashi, 荒井 創, Haruno Murayama, Kenji Sato, Hideyuki Komatsu, Hajime Tanida, Yukinori Koyama, 内本 喜晴, Zempachi Ogumi.  
English: Ikuma Takahashi, Hajime Arai, Haruno Murayama, Kenji Sato, Hideyuki Komatsu, Hajime Tanida, Yukinori Koyama, Yoshiharu Uchimoto, Zempachi Ogumi.  
Language English 
Journal/Book name
Japanese:Physical Chemistry Chemical Physics 
English:Physical Chemistry Chemical Physics 
Volume, Number, Page Vol. 18        pp. 1897
Published date Dec. 3, 2015 
Publisher
Japanese: 
English: 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
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DOI https://doi.org/10.1039/c5cp05535k
Abstract LiNi0.5Mn1.5O4 (LNMO) is a promising positive electrode material for lithium ion batteries because it shows a high potential of 4.7 V vs. Li/Li+. Its charge–discharge reaction includes two consecutive phase transitions between LiNi0.5Mn1.5O4 (Li1) 2 Li0.5Ni0.5Mn1.5O4 (Li0.5) and Li0.5 2 Ni0.5Mn1.5O4 (Li0) and the complex transition kinetics that governs the rate capability of LNMO can hardly be analyzed by simple electrochemical techniques. Herein, we apply temperature-controlled operando X-ray absorp- tion spectroscopy to directly capture the reacting phases from 20 1C to 40 1C under potential step (chronoamperometric) conditions and evaluate the phase transition kinetics using the apparent first-order rate constants at various temperatures. The constant for the Li1 2 Li0.5 transition (process 1) is larger than that for the Li0.5 2 Li0 transition (process 2) at all the measured temperatures, and the corresponding activation energies are 29 and 46 kJ mol 1 for processes 1 and 2, respectively. The results obtained are discussed to elucidate the limiting factor in this system as well as in other electrode systems.

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