喷雾干燥法制备Li_(1.2)Mn_(0.4+x)Ni_xCr_(0.4-2x)O_2及其结构与电化学特征  

Preparation,Structure and Electrochemical Properties of Li_(1.2)Mn_(0.4+x)Ni_xCr_(0.4-2x)O_2 by Spray-Dry Process

作　　者：张茜[1] 贺诗词[1] 刘伟伟[1] 方国清[1] 金子信悟[1] 杨裕生 郑军伟[1] 李德成[1] 

机构地区：[1]苏州大学化学电源研究所江苏省锂电池材料重点实验室,苏州215006 [2]北京防化院,北京100083

出　　处：《无机化学学报》2012年第12期2501-2507,共7页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.20973200)资助项目

摘　　要：利用喷雾干燥法合成了富锂三元正极材料Li1.2Mn0.4＋xNixCr0.4-2xO2（x=0，0．05，0．10，0．15，0．20，以下简称为SD1-SD5），并利用XRD，XPS，ICP，TEM，SEM等手段对材料进行结构，元素价态，形貌及电化学性能等方面的表征。SD1-SD5系列样品都具有层状结构，其所含的Cr元素为Cr^6＋和Cr^3＋共存，而Ni元素价态为＋2．5价，Mn元素为＋4价。SDl。SD4样品中由于存在非晶态的Li2CrO4，导致样品表现出强烈的吸湿性。这个问题可通过水洗处理来解决，且水洗处理对于改善该系列材料的电化学性能有明显的效果。SD1-SD5系列样品中，SD1与SD4样品电化学性能较好，以20mA·g^-1。的放电电流密度，在4．8—2．0V电压区间内，首次放电比容量分别为247和220mA·h·g^-1,经过20次充放电循环后，容量保持率分别为73％和78％。高温条件下SD1和SD4样品的首次放电比容量分别增大为256和237mA·h·g^-1，经过20次充放电循环后容量保持率分别为83％和99％。将充放电电压扩展为5．0~2．0V时，SD4样品首次放电比容量可以达到307mA·h·g^-1。Li1.2Mn0.4＋xNixCr0.4-2xO2（x=0, 0.05, 0.10, 0.15, 0.20） were synthesized by spray-drying process, which was named as SD1 to SD5, respectively. Their crystal structures, element valences and the electrochemical performances were investigated by XRD, XPS, ICP, SEM and TEM. All compounds have a typical feature of a Lirich layered solid solution material in terms of their crystal structures, and the valences of Ni and Mn are 2.5 ＋ and 4 ＋, respectively. As to the valence of Cr, both ＋3 and ＋6 co-exist in the samples from SD1 to SD4. Moreover, the present of amorphous Li2CrO4 gives rise to the strong hygroscopicity, which should be closed related to the poor electrochemical properties. Sample with water-washed treatment could effectively remove the amorphous Li2CrO4, and consequently improved its electrochemical properties. The washed SD4 has a reversible capacity of 237 mA·h·g^-1 and the capacity retention is about 99%, when the cell was operated at 50 ℃ in the range of 4.8～2.0 V. If it was operated in the range of 5.0～2.0 V at 50 %, the initial discharge capacity increases to 307 mA· h· g^-1

关 键 词：喷雾干燥法 水洗处理 元素价态 电化学性能 LI1 2Mn0 4+xNixCr0 4-2xO2 固溶体体系 

分 类 号：O614.111[理学—无机化学] O614.611[理学—化学]