固相法制备尖晶石型LiMn2O4的电化学性能

采用固相法在不同温度下(700℃,750℃,800℃和850℃)合成了尖晶石型锰酸锂·应用X射线衍射、扫描电镜、循环伏安和交流阻抗等技术对材料进行了研究·结果表明,不同温度合成样品的晶格常数均大于标准尖晶石型锰酸锂的晶格常数,颗粒细,粒径分布在0 2～0 4μm·循环伏安测试表明,锂离子脱嵌分两步进行;750℃下合成的样品循环伏安曲线对称性好,随着循环进行,电极表面形成钝化膜,并逐渐趋于稳定·交流阻抗测试表明,电极过程由一个参数控制转化为两个状态参数控制·

Electrochemistry Properties of Spinel LiMn2O4 Prepared by Solid Reaction

The spinel LiMn2O4 was synthesized at 700, 750, 800 and 850°C separately by solid reaction, of which different samples were investigated via X-ray diffraction, scanning electron microscopy, cyclic voltammetry and AC impedance testing. The results showed that the lattice constants of all samples are greater than that of the standard spinel LiMn2O4, with finer grain size distributed in the range 0.2-0.4 μm. The cyclic voltammetric testing result indicated that the Li⁺ deinsertioninsertion process is performed in two steps and the electrode surface is passivated, then gradually stabilized in the cyclic process, especially the cyclic voltammetric curve of the sample synthesized at 750°C shows good symmetry. The AC impedance testing showed that the electrode process is controlled by two state parameters instead of one.