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Suppression of Mn–Ion‐Dissolution of LiNi 0.5 Mn 1.5 O 4 Electrodes in a Highly Concentrated Electrolyte Solution at Elevated Temperatures
Author(s) -
Doi Takayuki,
Shimizu Yusuke,
Matsumoto Ryo,
Hashinokuchi Michihiro,
Inaba Minoru
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701668
Subject(s) - electrolyte , dissolution , spinel , propylene carbonate , inorganic chemistry , electrode , solvent , lithium (medication) , molecule , chemistry , materials science , decomposition , ion , metallurgy , organic chemistry , medicine , endocrinology
Mn‐based active materials, such as LiMn 2 O 4 , are widely used for positive electrodes in lithium ion batteries, and spinel LiNi 0.5 Mn 1.5 O 4 is drawing much attention to realize 5‐V class batteries. However, the oxidative decomposition of electrolyte solution at high voltages and Mn‐dissolution of LiNi 0.5 Mn 1.5 O 4 are serious problems to be solved. These two drawbacks are more marked at elevated temperatures, and should be caused by free solvent molecules in electrolyte solution. In this study, highly concentrated electrolyte solution, which contains few free solvent molecules, was investigated to solve the problems. LiNi 0.5 Mn 1.5 O 4 electrodes worked at 50 o C in nearly saturated 7.25 mol kg −1 LiBF 4 / propylene carbonate (PC) electrolyte solution, whereas not in the nearly saturated 4.30 mol kg −1 LiPF 6 /PC. In addition, Mn‐ion dissolution from LiNi 0.5 Mn 1.5 O 4 was significantly suppressed in highly concentrated electrolyte solutions, and correlated to the fraction of free PC molecules in them.