Development and Characterization of LiMn2O4 Based Cathode Materials for Lithium-ion Batteries
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Date
2013
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by Azhar Iqbal
Abstract
Spinel LiMn2O4 is one of the most attractive positive electrode materials for Li-ion rechargeable batteries. In the present study, six series of low content bi-metal doped LiMn2O4 with nominal compositions of LiNixCryMn2-x-yO4, LiLaxZnyMn2-x-yO4, LiCuxCryMn2-x-yO4, LiCuxZnyMn2-x-yO4, LiNixCuyMn2-x-yO4 and LiNixZnyMn2-x-yO4 (where x = y = 0.01-0.05) were prepared by the sol-gel method. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) confirmed the formation of the pure as well as the doped spinel LiMn2O4 between 285 oC and 350 oC. However, well crystallized spinel phase verified from the X-ray diffraction studies was obtained at 750 oC. XRD measurements further confirmed that all the synthesized compounds crystallized as single phase products in the cubic spinel Fd3m space group. The results showed that doping LiMn2O4 with such small amount of metals has not affected the original spinel structure. Inductively coupled plasma optical emission spectrometry (ICP-OES) findings agreed the used nominal compositions. Energy dispersive X-ray analysis (EDX) also confirmed the purity of all the synthesized samples. SEM and TEM images showed that unlike the pure LiMn2O4, all the doped samples exhibited uniform size with smooth faceted polyhedral particles. The average particle size ranges from about 42 nm to 250 nm. High resolution TEM images also demonstrated the highly crystalline nature of all the six doped series.