Na/Mn摩尔比对层状O2结构Li_y[Li_(1/6)Mn_(5/6)]O_2的晶体结构及化学组成的影响

Influence of Na/Mn Mole Ratio in the Precursor on the Crystal Structure and Chemical Composition of Layered O2 Li_y[Li_ (1/6)Mn_ (5/6)]O_2

由高温焙烧法制备层状前驱体 Nax[Li1 /6 Mn5/6 ]O2 ,再经离子交换反应得到 O2结构层状产物Liy[Li1 /6 Mn5/6 ]O2 。采用离子交换和元素分析推测前驱体中 Li+ 位于层板上。 XRD测试结果表明 ,Liy[Li1 /6 Mn5/6 ]O2 属六方晶系 ,P3 ml空间群 ;激光粒度分析仪测定 Na0 .0 6 Li0 .6 5[Li0 .1 0 Mn0 .88]O2 的最可几粒径为 2 .88μm;BET法测定其比表面积为 4.68m2 / g;TEM显示其形貌为存在缺陷的层状六方结构。XRD和元素分析结果表明 ,反应物 n(Na) / n(Mn)比直接影响着前驱体及最终产物的晶体结构和化学组成。

The precursors Na_x[Li_ 1/6Mn_ 5/6]O_2 having P2 structure were synthesized by solid-state reaction at high temperature followed by calcination. The layered Li_y[Li_ 1/6Mn_ 5/6]O_2 was then obtained by refluxing precursor with an excess of LiBr in n-hexanol. Li+ was confirmed to be in the host layers by virtue of its slow rate of exchange with molten magnesium nitrate. XRD showed that the Li_y[Li_ 1/6-Mn_ 5/6]O_2 has a layered O2 structure with hexagonal space group P3ml. Laser particle size analysis of Na_ 0.06Li_ 0.65[Li_ 0.10Mn_ 0.88]O_2 gives a uniform particle size distribution with a maximum at 2.88 μm. BET surface area was 4.68 m2/g. The crystals of products possess a defected hexagonal plate-like morphology with stacking faults. XRD and elemental analysis confirmed that the n(Na)/n(Mn) ratio of the reagents shows a direct effect on the crystal structure and chemical composition of both the precusor and final product.