化学共沉淀法制备Li_xCoO_2的高温化学相变过程研究

Investigation of the High Temperature Crystal Phase Change of LiCoO_2 Prepared by Chemical Co-Precipitation Process

以从废旧锂离子电池中回收的钴、锂为原料制备了LiCoO_2粉体。讨论和分析了不同温度下的热处理对Li_xCoO_2结构的影响。随温度升高,立方相减少,六方层状相增多。600℃时尖晶石相向六方相转变,温度继续升高(650℃～800℃)只有六方层状结构存在。再升至较高温度,层状属性增强,结构出现不稳定性,锂出现挥发,在860℃左右,产生新的相变;经过高温XRD分析,900℃时,出现大量的立方相Li_xCo_(1-x)O和Co_3O_4,并随温度持续升高,六方LiCo_O_2相与立方Co_3O_4均有所减少,而立方Li_xCo_(1-x)O相增加,1050℃时以Li_xCo_(1-x)O为主,当x<0.07时,立方Li_xCo_(1-x)O为结构稳定相。

LiCoO2 powder was prepared by chemical co-precipitation process with cobalt carbonate and lithium carbonate recovered from spent lithium ion batteries as raw materials. The crystal phases of the products heat treated at different temperatures were discussed and analyzed. The results show that cubic phase diminishes and hexagonal layered phase increases with the temperature of heat treatment increasing; only hexagonal layered phase existes at 650 ℃～800℃. Continually increasing temperature leads to volatilization of Li and instability of structure, and new phase change takes place at 860℃. The results of high-temperature XRD show that volume of cubic LixCO1-xO and Co3O4 are presented at 900 ℃, but cubic LixCo1-xO becomes the dominating phase at 1050 ℃, which is the stable phase when x〈0.07.