碳包覆尖晶石LiMn2O4的制备及电性能

以碳凝胶为添加剂,采用熔融浸渍法合成碳包覆的尖晶石型LiMn2O4。通过X射线衍射和扫描电镜对材料的晶体结构和表观形貌进行了分析,结果显示所制备的材料是纯尖晶石结构,碳包覆的LiMn2O4颗粒无团聚现象。室温下,对碳包覆的LiMn2O4进行电化学测试,结果表明:以0.5C、1C、2C倍率进行充放电测试的首次放电比容量分别为119.5、114.7、108.0mAh/g;此外,碳的包覆增强了颗粒间的导电性,减少了LiMn2O4与电解液的接触面积,抑制了Mn的溶解,提高了电池的循环稳定性。交流阻抗测试表明,碳包覆可以降低电极反应过程中的电荷转移电阻。

Synthesis and electrochemical performance of carbon-coated LiMn2O4

Carbon-coated spinel LiMn2O4 composite cathode was synthesized by melt impregnating method using carbon xerogel as additive for Li-ion battery. The crystalline structure, morphology of particles were analyzed by X-ray diffraction and scanning electromicroscopy, the results show that the material obtained is pure spinel-type phase and the particles of carbon-coated LiMn2O4 have no aggregation. Galvanostatic charge-discharge tests of carbon-coated LiMn2O4 cathode were carried out at 0.5 C, 1 C, 2 C rate at room temperature, and the initial dis-charge capacity were 119.5, 114.7, 108.0 mAh/g, respectively. The carbon dispersed between the grains ensured a good electronic contact, restraining the dissolving of Mn,so that the cycling stabilization was enhanced. The electrochemical AC impedance spectroscopy shows that the charge transfer resistance reduces obviously during electrochemical reaction process.