Effect On The Structure Morphology And Electrical Properties Of Spinel LiMn₂O₄by Synthesis Of Special Micro/Nano Structure Manganese Oxide

As we all know, the working voltage of spinel LiMn2O4is3.8V (VS. Li) and the theoretical capacity is148mAh/g. Moreover, the LiMn2O4material owns many overwhelming advantages, such as abundant resource、low cost、well safety、no environmental pollution and facile synthesis and so on, for this reason, it is obviously that it is identified as an ideal material. But, the fast fading of the capacity inhibits its developments and employments in the field of lithium ion battery. In order to improve the cycling performance researchers make effort to optimize the synthetic method, doped with different elements, surface modification and finding effective electrolyte at present. Researchers show that the properties of LiMn2O4are depend on its crystal morphology and crystallinity in a great degree, and the nano-crystallization of electrode material is one of the effective methods to improve electrode capacity and power performance. This article mainly studied at the anode materials of LiMn2O4from the following aspects.1. Facile synthesis of hollow microspheres of LiMn2O4as high-performance cathodes for Lithium-ion batteries:We synthesized hollow micro-spherical LiMn2O4successfully by two common materials MnSO4·H2O,Na2S2O8in ordinary pressure and certain temperature. There is no need other additive and stirring. Besides, it is consists of nanowires entirely. The obtained LiMn2O4synthesized by using the mentioned γ-MnO2as precursor is combination of well-crystallized micron-sized single crystals. The results of the experiment suggest that LiMn2O4with this structure possess high specific capacity、high rate performance and superior cycling capability. Furthermore, we only use a simple enough method, the mild conditions and easily operating means. So, there is no doubt that it is an ideal cathode material for lithium ion battery.2.The synthesis and performance of large particle of spinel LiMn2O4:In this reaction,1.5mol/L MnSO4·H2O and1.5mol/L Na2S2O8were volume mixed at50℃in static for48h,then formed the target precursor power with multilayer core shell structure. Then experienced sintering process with high temperature.In end, we obtained the MnO2with cage structure with high crystallinity, low content of Na+. and large single-grain. We get sample polyhedron with a diameter of7μm, via sintering with LiOH·H2O at 800℃.The lower temperature can avoid the side-effect,which can decompose in higher temperature.The sample possess high crystallinity, the lower BET, and it is obviously have excellent charge-discharge performance, cycling performance and storing energy in high temperature.3. The research of the suitable sintering temperature about synthesizing LiMn2O4via β-MnO2nano-wire:Taking five grinded mixture of β1-MnO2and lithium salt, all of the five were heated to550℃for8h in muffle,then heated to700℃,750℃,800℃,850℃,900℃respectively for24h. We did research on a series testing of TG-DSC, BET, XRD and SEM of the obtained samples in order to get the reaction mechanism of β1-MnO2and lithium salt and compared with the sintering process of EMD and lithium salt to exploring the best temperature of sintering single crystallites via nano-structure precursor and lithium salt. The necessary temperature both can avoid the uniting of the sample particles and decomposing of the sample in high temperature.