Chung, Kyung Yoon Yoon, Won-Sub McBreen, James Yang, Xiao-Qing Oh, Si Hyoung Shin, Ho Chul Cho, Won Il Cho, Byung Won 2024-01-21T00:03:07Z 2024-01-21T00:03:07Z 2021-09-02 2007-12-06 0378-7753 https://pubs.kist.re.kr/handle/201004/133887 Synchrotron based in situ X-ray diffraction technique has been used to study the mechanism of capacity fading of LiCoO2 cycled to a higher voltage above the normal 4.2 V limit and to investigate the mechanism of capacity retention improvement by ZrO2 surface coating on LiCoO2 It was found that the capacity fading of LiCoO2 Cycled at higher voltage limit is closely related to the increased polarization rather than the bulk crystal structure damage. The capacity of uncoated LiCoO2 sample dropped to less than 70 mAh g(-1) when charged to 4.8 V after high voltage cycling. However, when the voltage limit was further increased to 8.35 V, the capacity was partially restored and the corresponding structural changes were recovered to the similar level as seen in fresh sample. This indicates that the integrity of the bulk crystal structure of LiCoO2 was not seriously damaged during cycling to 4.8 V. The increased polarization seems lobe responsible for the fading capacity and the uncompleted phase transformation of LiCoO2. The polarization-induced capacity fading can be significantly improved by ZrO2 surface coating. It was proposed that the effect of ZrO2-coating layer on the capacity retention during high voltage cycling is through the formation of protection layer on the surface of LiCoO2 particles, which can reduce the decomposition of the electrolyte at higher voltages. (C) 2007 Published by Elsevier B.V. English ELSEVIER CATHODE PHASES XRD In situ X-ray diffraction studies on the mechanism of capacity retention improvement by coating at the surface of LiCoO2 Article 10.1016/j.jpowsour.2007.06.242 1 JOURNAL OF POWER SOURCES, v.174, no.2, pp.619 - 623 JOURNAL OF POWER SOURCES 174 2 619 623 scie scopus 000252020500049 2-s2.0-36148995017 Chemistry, Physical Electrochemistry Energy & Fuels Materials Science, Multidisciplinary Chemistry Electrochemistry Energy & Fuels Materials Science Article; Proceedings Paper CATHODE PHASES XRD ZrO2-coated LiCoO2 in situ X-ray diffraction phase transitions lithium batteries