Synthesis of Lithium-Manganese-Oxide Spinels: A Study by Thermal Analysis (original) (raw)
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Synthesis and Properties of Lithium Manganese Spinels
2001
Li 1x Mn 2y Co y O 4 (x = 0-0.06, y = 0-0.15) spinels were prepared by solid-state reactions and solgel processing and were characterized by x-ray diffraction and scanning electron microscopy. The spinels offer satisfactory electrochemical performance and are potentially attractive as cathode materials for rechargeable lithium batteries.
Coexistence of two phases having space groups of Fd3m and P4332 in the Mg-doped LiMn2O4 spinel is being reported for the first time in this article. Mg-doped LiMn2O4 powders have been synthesized by sol–gel method using citric acid as a chelating agent. X-ray powder diffraction (XRD) studies show that the crystal structure of LiMgxMn2−xO4 for x<0.25 is a single-phase cubic spinel, which has space group of Fd3m. The cubic spinel structures having space group of Fd3m and P4332 are found to coexist in the compound for x=0.25. The structure becomes single-phase cubic spinel with space group P4332 for x>0.25. Field emission scanning electron microscopy (FESEM) shows that particle size of various synthesized powders ranges from 100 to 350 nm. Particle size decreases with increase in Mg content. Differential thermal analysis (DTA) and thermogravimetry (TG) studies show an exponential decay relationship between Mg-doping content and the decomposition temperature to form nonstoichiomet...
Low-temperature hydrothermal synthesis of spinel-type lithium manganese oxide nanocrystallites
Solid state ionics, 2003
A mild hydrothermal method has been developed to synthesize spinel-type lithium manganese oxide nanocrystallites directly from commercial LiOH, Mn(NO 3 ) 2 and H 2 O 2 at 90 -110 jC for 8 h. The as-prepared products were characterized by Xray diffraction (XRD), inductively coupled plasma -atomic emission spectroscopy and chemical analysis. The analysis results indicated that spinel-type lithium manganese oxides with the compositions of Li 1 + x Mn 2 À x O 4 À d (0.09 V x V 0.28, y < 0.05) could be obtained by varying the synthesis parameters, such as the concentration of LiOH solution used. Transmission electron microscopy (TEM) images showed that the obtained spinel at 110 jC was cubic-shaped with the average size of around 40 -50 nm. Finally, the thermal behaviors of the obtained lithium-rich spinel Li 1.28 Mn 1.72 O 3.99 were investigated by thermogravimetric analysis (TG) and differential thermal analysis (DTA). D
Journal of Applied Electrochemistry, 2005
A low external temperature method (LETM) of active electrode material synthesis for lithium ion batteries has been proposed. The method consists of a two-step process, which is comprised of drying fine droplets of a solution of the starting compound in a liquid drying agent at 200°C, followed by calcination of the obtained precursor in a fluidised bed at a furnace temperature of 300°C. The method prevents uncontrolled growth of particles during the initial thermal pre-treatment and the final firing process. Lithium manganese spinel has been selected for describing the proposed LETM of synthesis. The properties of the spinel obtained by LETM are compared with those of a spinel obtained by the classical immobilised solid state synthesis at 750°C. On electrochemical cycling, the capacity loss after 100 cycles of the LETM spinel at 11% is significantly lower than that for the spinel prepared by solid state methods (21.5%). However, only 3% difference is seen in the total integral capacity over the 100 cycles between spinels prepared by the different methods.
FORMATION OF SPINEL STRUCTURE IN SYNTHESIS PROCESS OF Li1.37Mn2O4 USING HYDROTHERMAL METHOD
Jurnal Sains Materi Indonesia, 2018
FORMATION OF SPINEL STRUCTURE IN SYNTHESIS PROCESS OF Li1.37Mn2O4 USING HYDROTHERMAL METHOD. Li1.37Mn2O4 is one form of Li1+xMn2O4 which is engineered from LiMn2O4 phase which is commonly used as a lithium cathode active ingredient. The crucial thing from Li1.37Mn2O4 synthesis is the spinel structure that is formed. This study aims to observe when the spinel structure of Li1.37Mn2O4 starts and when the transformation from a tetragonal structure into spinel occurs. The raw materials used are tetragonal LiOH and tetragonal MnO2. The synthesis was carried out using a hydrothermal method with a temperature of 200 oC with a variation of holding times of 50, 70, 90 and 110 hours. Observation of spinel structure was carried out using XRD and TEM. The results obtained were at the holding times of 50 and 70 hours, the spinel structure had not been formed. The spinel structure begins to form at 90 hours holding time which also indicates that the transformation from the tetragonal structure to...
Key Engineering Materials, 2004
Spinel LiMn 2 O 4 has been successfully prepared at a low temperature rapidly by microwave heating method. LiMn 2 O 4 fine particles can be easily prepared in a few minutes by microwave heating of γ-MnOOH powders in a LiOH+H 2 O 2 solution. This synthesis process can provide an efficient, economical and environmentally friendly way of preparation of spinel lithium manganese oxides. The spinel LiMn 2 O 4 phase formation was confirmed by XRD, XPS, TG-DTA and SEM.