凝胶燃烧法合成LiCoO_2超细粉体的研究

SYNTHESIS OF ULTROFINE LiCoO_2 POWDERS BY CITRATE-NITRATE GEL COMBUSTION PROCESS

以 ＬｉＮＯ３和 ＣＯ（ＮＯ３）２·６Ｈ２Ｏ为原料，柠檬酸为燃料．采用凝胶低温燃烧技术合成了 ＬｉＣｏＯ２超细粉体，并利用各种分析技术时柠檬酸和硝酸盐形成的凝胶及凝胶燃烧合成的粉体进行了研究．泞檬酸－硝酸盐凝胶在３５０－４００℃之间发生燃烧反应、得到黑色疏松粉体．Ｘ射线衍射分析表明，适当提高柠檬酸在凝胶中的含量．燃烧后得到的粉体晶粒尺寸显著减小：未经燃烧的粉体中除含有ＬｉＣｏＯ２外，还有ＣｏＯ，Ｌｉ２ＣＯ３等杂质相．但在４５０℃下经短时间锻烧后，杂质相消夫、其晶相为层状岩盐结构的高温 ＬｉＣｏＯ２相．扫描电镜和透射电镜观察发现，随着假烧温度的提高．ＬｉＣｏＯ２粉体的粒径有所增大，但远小于在相同煅烧条件下用固相反应法制备的ＬｉＣｏＯ２粉体，这表明采用燃烧法更适于合成具有单一相结构的，可在低温条件下烧结的超细ＬｉＣｏＯ２粉体．

The ultrofine LiCoO2 powders were synthesized using LiNO3 and Co(NOa)2 6H20 as the starting materials and citrate acid as the fuel by the gel combustion process. Several analysis techniques were used to study the gel and the synthesized powders. It was found that the gel could be burnt at about 350-400℃ and the black and loose powders were easily obtained. XRD analysis shows that mild excess fuel was more in favor of the synthesis of LiCoO2 powders with fine crystallite size in comparison with stoichiometric fuel. After being calcined at 550℃ or above, the well developed high temperature LiCoO2 phase was obtained. SEM and TEM observations show that the particle size of LiCoO2 is increased with the increase of calcination temperature. The size of LiCoO2 powders prepared by combustion process is much less than that prepared by solid-state reaction process.