Co、Cr、Al掺杂LiMnO_2的离子交换法制备及其性质研究

Preparation and characterization of ion exchange derived Co,Cr and Al doped LiMnO_2

采用离子交换法制备Co,Cr及Al掺杂LiMnO2,通过X射线衍射、扫描电子显微镜和恒电流充放电等技术检测和分析合成产物的物相、形貌及电化学性能。研究表明掺杂后LiMnO2仍然保持原来的结构,但晶粒形貌发生了改变,晶格常数总体变小。与未掺杂的LiMnO2相比,Co、Cr及Al掺杂LiMnO2具有更高的放电容量和更好的循环性能。随着掺杂量的增加,Co、Cr及Al掺杂LiMnO2的放电容量逐步下降,但循环性能不断改善。在掺杂的LiMnO2中,LiMn0.95Cr0.05O2的放电容量最高,达到198.1mAh/g,而LiMn0.85Al0.15O2的放电容量最小,LiMn0.90Cr0.10O2循环性能最好,而Co掺杂的循环性能最差。

Cathode materials of Co, Cr and Al doped LiMnO2 for lithium ion battery were prepared by ion exchange. Phase identification, surface morphology and electrochemical properties were studied by X-ray diffraction, scanning electron microscopy and galvanostatic charge-discharge experiments. The results show that the crystal parameter of doped LiMnO2 is generally smaller than the undoped LiMnO2. The surface morphology of the doped LiMnO2 is different from LiMnO2, while both structures are the same. All the doped LiMnO2 offers higher discharge capacity and better cycling performance than LiMnO2. The discharge capacity of the doped LiMnO2 decreases, yet the cycling performance improves with the increase of doping concentration. For these doped LiMnO2, LiMno.gs Cr0.05 O2 offers the highest discharge capacity of 198.1 mAh/g and LiMn0.85 Al0.15 O2 offers the lowest. The cycling performance of LiMn0.90 Cro.10 O2 is the best, while cobalt doped LiMnO2 is the worst.