富锂锰基层状正极材料0.6Li[Li_(1/3)Mn_(2/3)]O_2·0.4LiNi_xMn_yCo_(1-x-y)O_2(x<0.6,y>0)的制备及性能研究

Preparation and Performance of Lithium-Rich Manganese Layered Materials 0.6Li[Li_(1/3)Mn_(2/3)]O_2·0.4LiNi_xMn_yCo_(1-x-y)O_2(x<0.6, y > 0)

采用碳酸盐共沉淀法合成出前驱体,然后通过高温固相法制备了富锂锰基材料0.6Li[Li1/3Mn2/3]O2·0.4Li NixMnyCo1-x-yO2（x〈0.6,y〉0）.使用扫描电镜（SEM）、X射线衍射（XRD）以及电化学方法等手段进行了表征.高温原位XRD测试结果表明,随着温度和Ni含量增加,材料的晶胞参数发生较大变化,温度达800 o C时,高Ni组成的材料阳离子混排现象严重,并伴有尖晶石相生成.电性能测试结果表明,在充放电电压为2.0~4.6 V、电流密度20m A·g-1条件下,低Ni含量材料表现出较好的电化学性能,首周放电容量达260.1 m Ah·g-1,首次效率为83.2%,经过50次循环后放电容量保持率高达99.7%,且在电池循环过程中,放电电压平台下降较少.

Lithium-rich manganese based cathode materials .6Li[Li1/3Mn2/3]O2.0.4LiNixMnyCO1-x-yO2（x 〈 0.6, y 〉 0） were syn- thesized by carbonate co-precipitation and high temperature solid-state reaction. The structures and morphologies of the as-prepared materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）. The results of high temperature in-situ XRD test show that the lattice parameters change significantly with increasing temperature and Ni content. The cation mixing gets serious and the spinel phase appears in the high Ni content samples when the temperature is up to 800 ℃. Under voltages ranging from 2.0 to 4.6 V, the lower Ni content sample has the highest discharge capacity of 260.1 mAh. g.l （the initial coulombic efficiency of 83.2%） at current density of 20 mA.g-1, and the discharge capacity retention is up to 99.7% with the relatively smaller voltage de- cay after 50 cycles.