高容量锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的制备与工艺优化

Preparation and process optimization of LiNi0.5Co0.2Mn0.3O2 as cathode material for high capacity lithium-ion battery

摘要:

采用氢氧化物共沉淀法合成前驱体Ni_0.5Cc_0.2Mn_0.3H(OH)₂,进一步用高温固相法与锂源共混煅烧得到LiNi_0.5Co_0.2Mn_0.3O₂。初步探讨了前驱体与锂源在高温煅烧过程中的质量变化及煅烧工艺对材料结构和性能的影响。热重分析(TGA)表明在煅烧过程中750℃后材料质量几乎没有变化。X射线衍射(XRD)对750℃-900℃的材料进行结构分析,结果表明所有材料具有良好的α-NaFeO₂层状结构和较小的阳离子混排度。扫描电镜(SEM)分析表明材料具有表面光滑,分布均匀的球形结构。横流充放电测试结果表明在850℃煅烧的材料具有最好的电学性能,在0.2C,2.5-4.6V测试条件下,其具有193.7mAh/g的首次放电容量,循环30次后的容量保持率为94.2%,并且具有最好的倍率性能。

Abstract:

The precursor Ni_0.5Co_0.2Mn_0.3(OH)₂ is synthesized by hydroxide co-precipitation method, further high temperature solid state method is used to obtain the LiNi_0.5Co_0.2Mn_0.3O₂ by mixing with lithium source. The quality change of the precursor and lithium source during the high temperature calcination process and the effect of calcination process on the structure and properties of materials are discussed. Thermal gravimetric analysis (TGA) shows that there is little change in the material quality during the calcination process after 750℃. X-ray diffraction (XRD) indicates that all samples, which are synthesized from 750℃ to 900℃, have good α-NaFeO₂ layered structure and small cation mixing degree. Scanning electron microscope shows that the material has a smooth surface and a uniform distribution of spherical structure. The material, calcined at 850℃, shows a initial discharge capacity of 193.7mA.h.g_-1 in the voltage range of 2.5?4.6V at 25℃ and 0.2C, with the capacity retention rate of 94.2% after 30 cycles, which delivers the best electrochemical properties, including the rate capability.