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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 30, Number 4
BKCSDE 30(4)
April 20, 2009 

 
Title
Thermal Behavior of LixCoO2 Cathode and Disruption of
Solid Electrolyte Interphase Film
Author
Chil Hoon Doh*, Dong Hun Kim, Jung Hun Lee, Duck Jun Lee, Bong Soo Jin, Hyun Soo Kim, Seong In Moon, Younggi Hwang, Angathevar Veluchamy*
Keywords
Cathode, LixCoO2, Thermal analysis, Thermal stability, Solid electrolyte film
Abstract
Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and ion chromatography(IC) were employed to analyze the thermal behavior of LixCoO2 cathode material of lithium ion battery. The mass loss peaks appearing between 60 and 125℃ in TGA and the exothermic peaks with 4.9 and 7.0 J/g in DSC around 75 and 85 oC for the LixCoO2 cathodes of 4.20 and 4.35 V cells are explained based on disruption of solid electrolyte interphase (SEI) film. Low temperature induced HF formation through weak interaction between organic electrolyte and LiF is supposed to cause carbonate film disruption reaction, Li2CO3 + 2HF → 2LiF + CO2 + H2O. The different spectral DSC/TGA pattern for the cathode of 4.5 V cell has also been explained. Presence of ionic carbonate in the cathode has been identified by ion chromatography and LiF reported by early researchers has been used for explaining the film SEI disruption process. The absence of mass loss peak for the cathode washed with dimethyl carbonate (DMC) implies ionic nature of the film. The thermal behavior above 150 oC has also been analyzed and presented.
Page
783 - 786
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