XPS Investigation of the Electrolyte Induced Stabilization of LiCoO[subscript 2] and "AIPO[subscript 4]"-Coated LiCoO[subscript 2] Composite electrodes
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XPS investigation.pdf
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Author(s)
Quinlan, Ronald A.
Mansour, Azzam N.
Lu, Yi-Chun
Kwabi, David Gator
Shao-Horn, Yang
Date Issued
December 2015
Journal
Journal of The Electrochemical Society
Publisher
Electrochemical Society
Citation
Quinlan, Ronald A., Yi-Chun Lu, David Kwabi, Yang Shao-Horn, and Azzam N. Mansour. “XPS Investigation of the Electrolyte Induced Stabilization of LiCoO2and ‘AlPO4’-Coated LiCoO2Composite Electrodes.” Journal of The Electrochemical Society 163, no. 2 (December 3, 2015): A300–A308.
Version
Final published version
Abstract
The “AlPO[subscript4]” coating has been shown to improve the electrochemical performance of LiCoO2 batteries. We previously showed that the “AlPO[subscript4]” coating promotes the formation of metal fluorides, which could act as a stable surface film and protect LiCoO[subscript2] from continuous degradation upon cycling. In this work, we removed the fluorine source in the LiPF[subscript6] salt by using the LiClO[subscript4] salt and investigated the effectiveness of the “AlPO[subscript4]” coating. Interestingly, the “AlPO[subscript4]” coating was found to improve the voltage efficiency and capacity retention when cycling in the LiPF[subscript6] electrolyte, but was detrimental when cycling in the LiClO[subscript4] electrolyte. XPS revealed that the “AlPO[subscript4]” coating promotes the formation of metal fluoride in both electrolytes, with the surface film formed in LiClO4 being more electrically resistive compared to that formed in LiPF[subscript6]. The source of fluorine in the coated electrode cycled in LiPF[subscript6] is largely attributed to the LiPF[subscript6] salt whereas the source of fluorine in the coated electrode cycled in LiClO[subscript4] is the binder PVDF. We believe that the coating could react with HF impurity in the LiPF[subscript6] electrolyte or from the binder PVDF and form stable metal fluoride films on the surface.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Electrochemical Energy Laboratory
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Creative Commons Attribution 4.0 International License
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DOI of Published Version
https://doi.org/10.1149/2.0851602jes
