Coating of spinel LiNi0.5Mn1.5O4 cathodes with SnO2 by an electron cyclotron resonance metal-organic chemical vapor deposition method for high-voltage applications in lithium ion batteries

Abstract

Tin oxide coating by employing electron cyclotron resonance metal-organic chemical vapor deposition was performed on 5 V-class spinel LiNi0.5Mn1.5O4 cathode electrodes prepared by a conventional tape-casting method. The pristine and SnO2-deposited LiNi0.5Mn1.5O4 electrodes were characterized by X-ray diffraction, field-emission electron probe microanalyzer, field-emission scanning electron microscopy, Auger electron spectroscopy, charge-discharge measurements, and electrochemical impedance spectroscopy were evaluated in lithium cells using the fabricated electrodes. The SnO2-deposited LiNi0.5Mn1.5O4 electrodes exhibited better rate capability at room temperature and superior electrochemical performance during the storage test evaluated at 60 degrees C in a fully charged state than the pristine LiNi0.5Mn1.5O4 electrode. Also, surface modification of the LiNi0.5Mn1.5O4 electrode was found by impedance analyses to be effective for suppressing the increase of the charge transfer resistance during the storage test at elevated temperatures.