Electrochemical cycling behavior of LiCoO2 cathode prepared by mechanical alloying of hydroxides

Well-ordered high-temperature LiCoO2 (HT-LiCoO2) is synthesized by mechanical alloying (MA) of LiOH.H2O and Co(OH)(2) powders and subsequent firing. Its electrochemical properties are investigated. The maximum discharge capacity of a sample mechanically alloyed and fired at 600 degreesC for 2 h is 152 mAh g(-1) at the C/40 rate, which is comparable to that obtained from a sample made by conventional solid state reactions. The cycleability is inferior, however, due to a relatively low crystallinity, When the firing temperature is increased to 850 degreesC, the first discharge capacity of 142 mAh g(-1) at the C/5 rate is increased by more than 10%, and retains 93% of its maximum value after 30 cycles. These cycling properties are about the same, or slightly higher, than those synthesized by firing a sample mixture of the same starting materials at 600 degreesC for 8 h and then at 850 degreesC for 24 h. Consequently, given the lower firing temperature and/or reduced reaction time, MA could prove a promising synthetic process for cathode materials used in rechargeable lithium batteries. (C) 2002 Elsevier Science B.V. All rights reserved.