Improved electrochemical performance of Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(2) cathode material by fluorine incorporation

High capacity cathode materials Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(2-x)F(x) (x=0, 0.05 and 0.10) have been synthesized by a sol-gel method using NH(4)F as F source. The effects of fluorine content on the structure, morphology and electrochemical performance of the Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13...

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Bibliographic Details
Published in:Electrochimica acta 2013-08, Vol.105, p.200-208
Main Authors: Zheng, Jianming, Wu, Xiaobiao, Yang, Yong
Format: Article
Language:English
Subjects:
Cathodes
Doping
Electrochemical impedance spectroscopy
Electrodes
Electrolytes
Fluorine
Performance enhancement
X-ray photoelectron spectroscopy
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Summary:High capacity cathode materials Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(2-x)F(x) (x=0, 0.05 and 0.10) have been synthesized by a sol-gel method using NH(4)F as F source. The effects of fluorine content on the structure, morphology and electrochemical performance of the Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(2-x)F(x) have been extensively studied. With fluorine doping, cycling stability of Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(2-x)F(x) is significantly improved because of the stabilization of the host structure. Li[Li(0.2)Mn(0.54)Ni(0.13)Co(0.13)]O(1.95)F(0.05) shows a capacity retention of 88.1 % after 50 cycles at 0.2C at room temperature, much higher than that of 72.4% for pristine one. The improvement mechanism of fluorine doping has been investigated by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that fluorine incorporation stabilizes the electrode/electrolyte interface by suppressing the formation of poorly conducting LiF in the SEI layer and thus maintains stable interfacial resistances. As compared to the enhanced material structure, the stabilized electrode/electrolyte interface is the primary factor contributing to the improved electrochemical performance. In addition, the thermal stability of fully delithiated electrode is also greatly improved by fluorine doping.
ISSN:0013-4686