摘要
以氢氧化锂,醋酸锰和草酸为原料,采用低热固相反应法于350～700℃下直接通过热处理制备了锂离子电池正极材料r-LiMnO2粉体样品.X射线衍射分析表明,采用该法得到的样品与LiCoO2具有类似的晶型.由于Mn3+的Jahn-Teller效应使r-LiMnO2与同样方法合成的LiCoO2及LiCo0.8Ni0.2O2相比,晶胞形状变得更加扁平,晶胞体积增大.选区电子衍射研究表明高于600℃焙烧温度所得的r-LiMnO2样品中含立方尖晶石结构杂质相. 2.5～4.3V之间的充放电测试结果表明,样品的充放电容量随焙烧温度的升高而增大,但高于600℃的样品具有3V和4V两个充放电平台,而350～500℃的样品只有一个3V充放电平台,并且循环过程中结构非常稳定.
LiMn02 compounds with rhombohedral structure were prepared by the low-heating solid-state reaction method at the temperature range of 350-700℃. The powder X-ray diffraction technique was applied to investigate the structures of the obtained samples. XRD result shows that the structures of these samples are the same as that of LiCoO2- Compared with LiCoO2 and LiCo0.8Ni0.2O2 prepared by the same method, the lattice parameter of r-LiMnO2, c/α, is relatively smaller due to the Jahn-Teller deformation. Selected-area electron diffraction and XRD results indicate the existence of the cubic spinel impurities in the r-LiMnO2 samples sintered at 600℃ and 700℃. The tests of charge/discharge show that the samples prepared above 600℃ have two voltage plateaus of 3V and 4V, of which the plateau at 4V is related to the cubic spinel impurities. Whereas, the samples obtained below 500℃ present only one plateau of 3V. Especially, the sample obtained at 500c℃ exhibits good structural stability in lithium-ion intercalation/deintercalation processes.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第2期313-319,共7页
Journal of Inorganic Materials
基金
留学回国人员基金(教外司留(2000)479)
