Papers by Keyword: Lithium Manganese Oxide

Abstract: A facile topochemical route has been developed to synthesize porous LiMn₂O₄ spheres by using molten LiOH and porous Mn2O3 spheres as a precursor. The formation of porous LiMn₂O₄ spheres was inherited from porous Mn₂O₃ spheres which were obtained from the thermal decomposition of the MnCO₃ precursors and the presence of pores was confirmed by transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM). When applied as cathode materials for rechargeable lithium-ion batteries, it shows good capacity retention after cycling. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn₂O₄ spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries.

Abstract: In the paper, Li1+xMn2-xO4 are synthesized by ball-milling method and coprecipitation method. The phases of three compounds have been analyzed by X-ray diffraction to compare diffraction peak, crystal system and crystal lattice′ s size. Advisedly, the results show that a compound has more purity phase and better crystallinity. Synthetic method and reaction conditions of this compound are as follows: via coprecipitation method, heat the sample at 250°C for 4h in air, followed by heating at 750°C for 36h in air. This analysis provides a reasonable and valuable thinking for research of the structures of Li1+xMn2-xO4. And it is propitious to develop the positive material of lithium battery.

Abstract: Based on preparing high purity powdered lithium ion-sieve precursor LiMn2O4, using lithium carbonate and manganese carbonate as raw materials, through roasting at high temperature of 800°C, laminar lithium ion-sieve precursor was prepared by commixing poly (vinyl chloride) (PVC) and powdered precursor in DMF (N, N-dimethylformamide) as solvent, and then powder and lithium ion-sieve flat sheet membrane was obtained through washing with HCl solution respectively. Their adsorption capacity and morphology was also characterized. The results show that both powdered lithium ion-sieve and laminar one have high adsorption capacity and selectivity for Li in solutions, and the effect of their retest is good. All these can provide a good foundation for the further study on lithium ion-sieve flat sheet membrane and lithium extraction from seawater.

Abstract: Surface modification on the electrode has a vital impact on lithium-ion batteries, and it is essential to probe the mechanism of the modified film on the surface of the electrode. In this study, a Li2O-2B2O3 film was coated on the surface of the cathode material by solution method. The cathode powders derived from co-precipitation method were calcined with various weight percent of the surface modified glass to form fine powder of single spinel phase with different particle size, size distribution and morphology. The thermogravimetry/differential thermal analysis was used to evaluate the appropriate heat treatment temperature. The structure was confirmed by the X-ray diffractometer along with the composition measured by the electron probe microanalyzer. From the field emission scanning electron microscope image and Laser Scattering measurements, the average particle size was in the range of 7-8µm. The electrochemical behavior of the cathode powder was examined by using two-electrode test cells consisted of a cathode, metallic lithium anode, and an electrolyte of 1M LiPF6. Cyclic charge/discharge testing of the coin cells, fabricated by both coated and un-coated cathode material, provided high discharge capacity. Furthermore, the coated cathode powder showed better cyclability than the un-coated one after the cyclic test. The introduction of the glass-coated cathode material revealed high discharge capacity and appreciably decreased the decay rate after cyclic test.