氢氧化物共沉淀法制备LiMn_(0.45)Ni_(0.45)Co_(0.1)O_2正极材料的反应条件

Preparation Conditions of LiMn_(0.45)Ni_(0.45)Co_(0.1)O_2 via Hydroxide Co-precipitation

通过氢氧化物共沉淀法制备了Mn0.45Ni0.45Co0.1(OH)2,研究了反应条件对产物形貌特征的影响,重点研究了F-离子对产物形貌特征、振实密度的影响.利用前述产物通过高温固相合成法制备了高密度的LiMn0.45Ni0.45Co0.1O2和LiMn0.45Ni0.45Co0.1O1.96F0.04正极材料,并研究了F元素掺杂对循环性能的影响.结果表明,在沉淀体系中加入F-,可以改善产物的形貌特征和振实密度.SEM测试结果表明,产物具有良好的形貌;XRD测试表明,产物具有良好的层状结构,无杂质相存在.在充放电电压区间为2.8-4.4V,电流密度为30mA·g-1时,LiMn0.45Ni0.45Co0.1O2和LiMn0.45Ni0.45Co0.1O1.96F0.04首次放电容量均为157mAh·g-1,经过50次循环,放电容量保持率分别为72.6%和86.0%,F元素的掺杂可以明显改进材料的循环性能.

Mn0.45Ni0.45Co0.1（OH）2 was prepared via improved hydroxide co-precipitation. The effect of reaction condition on the shape of the product, and the effect of F^- ion on the morphology and tap-density of the product were studied. LiMn0.45Ni0.45Co0.1O2 and LiMn0.45Ni0.45Co0.1O1.96F0.04 were prepared by mixing this metal hydroxide with 5% excess LiOH followed by heat-treatment. The effect of F doping on the cycling performance of the prodct was investigated. The morphology and tap-density of the product were improved through the addition of F^- in co-precipitation system. The product was characterized using X-ray diffraction （XRD）, scanning electron microscope （SEM） and charge-discharge tests. It can be seen from the SEM results that the product has a good shape. The XRD studies showed that the material had a well-ordered layered structure without impurity phase. The initial capacities of both LiMn0.45Ni0.45Co0.1O2 and LiMn0.45Ni0.45Co0.1O1.96F0.04 are 157 mAh·g^-1 at a charging potential between 2.8 and 4.4 V and a current density of 30 mA·g^-1. The 72.6% and 86.0% discharge capacities were retained at the end of 50 charge-discharge cycles, respectively. It is shown that the F doping can obviously improve the cycling performance of the product.