Surface chemistry study of LiCoO2 coated with alumina
The surface chemistry of the Al2O3-coated LiCoO2 prepared under heat treatment at 80-800℃ was studied by SEM, XRD, IR, XPS and NMR spectroscopy combined with electrochemical testing. It is shown that the particle bulk is free from dopant. XPS A12s core-level spectrum of the coated LiCoO2 differs from that of α-Al2O3 and is associated with Al oxyhydroxide. 27Al NMR spectra of the samples prepared at 80-600℃ consist of intensive asymmetric peak with maximum at 4.8-6.2 ppm (Al in an octahedral coordination free from Co in the second coordination sphere) and two less intensive ones at ～55-56 and ～61-62 ppm. On the other hand, the spectrum of the 800℃ sample has no peak near 0 ppm, but has a series of peaks in the range of 26～62 ppm with an interval of about 7 ppm, characteristic of Al octahedral environment with neighboring Al number ranging from 6 to 0. This indicates that the shell consists mostly of amorphous oxyhydroxide in the first case and of LiCo(1-y)AlyO2 solid solution in the second. Electrochemical testing shows a significant increase in discharge capacity (>150 mAh/g) and improved cyclability of the coated samples heated below 600℃, while after heat treatment at 800℃, the capacity of composite cathode fades quickly.
LiCoO2 Al2O3 coating NMR XPS Cycling
Nina Kosova Evgeniya Devyatkina Arseny Slobodyuk Vasily Kaichev
Institute of Solid State Chemistry and Mechanochemistry SB RAS.18 Kutateladze, 630128 Novosibirsk, R Institute of Chemistry FEB RAS, 159 pr.100 Centenary of Vladivostok, 690022 Vladivostok, Russia Boreskov Institute of Catalysis SB RAS, 5 pr.Lavrenteva, 630090 Novosibirsk, Russia
国际会议
The 16th International Conference on Solid State Ionics(第十六届国际固态离子学会议)
上海
英文
1745-1749
2007-07-01（万方平台首次上网日期，不代表论文的发表时间）