Mechanism study of enhanced electrochemical performance of ZrO2-coated LiCoO2 in high voltage region

作者：Hwang B J^*; Chen C Y; Cheng M Y; Santhanam R; Ragavendran K

来源：Journal of Power Sources, 2010, 195(13): 4255-4265.

DOI：10.1016/j.jpowsour.2010.01.040

• Lithium cobalt oxide
• Zirconia coating
• Stability
• High voltage
• Lithium ion battery
• Cathode

In this study, the mechanism of enhanced performance of ZrO2-coated LiCoO2 especially at high potential range is systematically investigated. Firstly, when overcharging to 4.5 V (higher than 4.2 V. the normal cutoff charging potential), phase transformation from H1 to H2 takes place with less volume expansion for ZrO2-coated LiCoO2 (1.2% and 2.2% for as-received one). EIS analysis indicates the growth of interfacial impedance during charging/discharging can be effectively suppressed with ZrO2 coating on the LiCoO2 surface. It is demonstrated as well that cation mixing of the cycled LiCoO2 caused by re-intercalation of dissolved Co2+ is inhibited with the ZrO2 coating on the LiCoO2. Therefore the ZrO2-coated LiCoO2 shows great enhancement in the electrochemical properties with 85% capacity retention after 30 cycles from 3 to 4.5 ZrO2 at a rate of 0.5C. Nevertheless, under the same evaluation process, the as-received LiCoO2 possesses only 21% capacity retention, which is resulted from the formation of polymeric layers by the electrolyte decomposition on its surface, the higher volumetric changes during charging/discharging and possible cation mixing by re-intercalation of the dissolved Co2+.

• 出版日期2010-7-1