Electrochemical cycling behavior of LiCoO sub(2) cathode prepared by mechanical alloying of hydroxides

Well-ordered high-temperature LiCoO sub(2) (HT-LiCoO sub(2)) is synthesized by mechanical alloying (MA) of LiOH times H sub(2)O and Co(OH) sub(2) powders and subsequent firing. Its electrochemical properties are investigated. The maximum discharge capacity of a sample mechanically alloyed and fired at 600 degree C for 2 h is 152 mAh g super(-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 degree C, the first discharge capacity of 142 mAh g super(-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 degree C for 8 h and then at 850 degree C 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. copyright 2002 Elsevier Science B.V. All rights reserved.