软化学法合成正交结构LiMnO_2及其电化学性能

研究以氢氧化锂和三氧化二锰为原料,用软化学法制备具有正交结构的锂离子电池正极材料LiMnO2。用X射线衍射法确定了材料的结构,用扫描电镜考察了材料形貌和反应时间的关系,观察结果显示得到的LiMnO2的粒子尺寸在300~500nm。结合循环伏安法和交流阻抗分析研究了合成条件对材料组织结构、尺寸与电化学性能的影响。材料的电化学性能测试结果表明,合成的正交扭曲结构LiMnO2(o-LiMnO2)材料在电化学过程中初期表现了较好的电化学性能。但材料在电化学过程中逐步向尖晶石结构相LiMn2O4转变,容量产生衰减,其循环寿命有待更进一步改善。

Synthesis and electrochemical properties of orthorhombic structure LiMnO_2

LiMnO_2 samples were prepared as cathode materials for lithium ion batteries by soft-chemical synthesis from LiOH and Mn_2O_3.X-ray diffraction patterns of prepared samples were identified as the layered LiMnO_2 with orthorhombic structure(o-LiMnO_2).The particle size of the o-LiMnO_2 materials was about 300～500 nm by the scanning electron microscopy(SEM).Cycling voltammetry and electrochemical impedance spectroscopy(EIS)technique were used to studied the correlation between the structure and grain sizes of layered LiMnO_2 and its electrochemical properties.The electrochemical performance of the sample as a cathode materials for lithium ion batteries was studied by galvanostatic method.The obtained o-LiMnO_2 showed a good cycling behavior.However,its structure transformed into the spinel phase LiMnO_2O_4 and capacity fading during cycling.