Abstract
The effect of coating the high voltage spinel cathode LiMn 1.5Ni0.5O4 with three metal oxide thin layers is discussed. Instead of the typical powder electrodes with poorly defined surface coatings, thin film electrodes were prepared with well-defined oxide coating thicknesses to investigate the influence of coating on surface reactivity via X-ray photoelectron spectroscopy (XPS). ZnO is found to decompose during the first charge whereas Al2O3 and ZrO2 are stable for more than 100 cycles. ZrO2, however, importantly limits the available Li storage capacity of the electrochemical reaction due to poorer kinetics. Al2O3 offers the best results in term of capacity retention. Upon cycling, the evidence of a signal at 75.4 eV in the Al2p binding energy spectrum indicates the partial fluorination of Al 2O3 into, perhaps, Al2O2F 2. Moreover, the continuous formation of ethers, esters and Li xPOyFz compounds on the surface of the electrodes is found for all coating materials.
Original language | English |
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Pages (from-to) | 135-147 |
Number of pages | 13 |
Journal | Electrochimica Acta |
Volume | 90 |
DOIs | |
State | Published - Feb 15 2013 |
Funding
This research was supported by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory , managed by UT-Battelle, LLC, for the U. S. Department of Energy. The authors gratefully acknowledge Dr. Dafeng Chu and Prof. Dr. Thomas Kissel (Philipps Universität Marburg, Germany) for providing PEC samples.
Keywords
- Lithium manganese nickel oxide
- Lithium-ion
- Metal oxide coating
- Surface chemistry
- Thin films
- X-ray photoelectron spectroscopy