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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 25, Number 4
BKCSDE 25(4)
April 20, 2004 

 
Title
Cyclic Properties of Li[Co0,17Li0,28Mn0,55]O2 Cathode Material
Author
Yong Joon Park*, Young-Sik Hong, Xianglan Wu, Min Gyu Kim, Kwang Sun Ryu, Soon Ho Chang
Keywords
Cathode, Layered structure, Lithium battery, XANES, Cyclic properties
Abstract
A Li[Co0.17Li0.28Mn0.55]O2 cathode compound was prepared by a simple combustion method. The X-ray diffraction pattern showed that this compound could be classified as α-NaFeO2 structure type with the lattice constants of a = 2.8405(9) Å and c = 14.228(4) Å. According to XANES analysis, the oxidation state of Mn and Co ions in the compound were 4+ and 3+, respectively. During the first charge process, the irreversible voltage plateau at around 4.65 V was observed. The similar voltage-plateau was observed in the initial charge profile of other solid solution series between Li2MnO3 and LiMnO2 (M=Ni, Cr…). The first discharge capacity was 187 mAh/g and the second discharge capacity increased to 204 mAh/g. As the increase of cycling number, one smooth discharge profile was converted to two distinct sub-plateaus and the discharge capacity was slowly decreased. From the Co and Mn K-edge XANES spectra measured at different cyclic process, it can be concluded that irreversible transformation of phase is occurred during continuous cycling process.
Page
511 - 516
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