Pechini Synthesis of Nanostructured Li1.05M0.02Mn1.98O4 (M = Al3+ or Ga3+)

Amaral, Fábio Augusto do; Santana, Laiane Kálita; Campos, Irma Manrique; Fagundes, Wélique Silva; Xavier, Farlon Felipe Silva; Canobre, Sheila Cristina

doi:10.1590/1516-1439.361514

Cited by 4 publications

(3 citation statements)

References 24 publications

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“…The slurry mixture was sonicated for 30 min to form a homogeneous solution. Then it was spun (5000 rpm for 5 s) on a platinum plate and, in order to evaporate the solvent, the electrodes were dried at 120 ºC for 24 h in vacuum 20 .…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

PAni-coated LiFePO4 Synthesized by a Low Temperature Solvothermal Method

et al. 2018

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The composite LiFePO 4 /polyaniline was prepared by chemical synthesis to promote the intensification of the electrochemical properties for use as cathodes in lithium ion batteries. The X-ray diffraction (XRD) of LiFePO 4 synthesized by solvothermal method were indexed to the orthorhombic structure, according to the JCPDS 40-1499. The spectra Raman and FTIR showed a high degree of ordering of LiFePO 4 with interaction between LiFePO 4 surface with structure conjugate of conducting polymers. The cyclic voltammogram of the composite synthesized chemically showed a significant reduction in the value of ΔE p (ΔE p = 0.20 V) when compared to LiFePO 4 (ΔE p = 0.41 V), with lower charge transfer resistance values, indicating favoring electron transfer rate in the composite. Thus, the alternative synthesis route of the LiFePO 4 / PAni composite was easy to handle and allowed an increase in the electrochemical properties of the LiFePO 4 , compared to the traditional methods that require additional thermal treatments.

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Section: Electrochemical Characterizationmentioning

confidence: 99%

PAni-coated LiFePO4 Synthesized by a Low Temperature Solvothermal Method

et al. 2018

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“…Xiong et al [ 47 ] studied LMO doping with multiple cations (Cu, Al, and Ti) and established that multiple doping was effective in improving retention capacity at temperatures of 25 °C to 50 °C, maintaining a high rate capability up to 12C (C represents the numerical value of rated capacity of a battery, in Ah) and reducing Mn dissolution. Amaral et al [ 48 ] reported time and temperature effects of thermal treatment for Ga- and Al-doped LMO synthesis. They identified spinel phase formation at a temperature of 750 °C for a calcination time of 2 h and determined that the specific capacity of doped ones was lower than pure spinel.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and Thermodynamic Studies on Synthesis of Mg-Doped LiMn2O4 Nanoparticles

2020

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In this work, a first study on kinetics and thermodynamics of thermal decomposition for synthesis of doped LiMn2O4 nanoparticles is presented. The effect of Mg doping concentration on thermal decomposition of synthesis precursors, prepared by ultrasound-assisted Pechini-type sol–gel process, and its significance on nucleation and growth of Mg-doped LiMn2O4 nanoparticles was studied through a method based on separation of multistage processes in single-stage reactions by deconvolution and transition state theory. Four zones of thermal decomposition were identified: Dehydration, polymeric matrix decomposition, carbonate decomposition and spinel formation, and spinel decomposition. Kinetic and thermodynamic analysis focused on the second zone. First-order Avrami-Erofeev equation was selected as reaction model representing the polymer matrix thermal decomposition. Kinetic and thermodynamic parameters revealed that Mg doping causes an increase in thermal inertia on conversion rate, and CO2 desorption was the limiting step for formation of thermodynamically stable spinel phases. Based on thermogravimetry experiments and the effect of Mg on thermal decomposition, an optimal two-stage heat treatment was determined for preparation of LiMgxMn2-xO4 (x = 0.00, 0.02, 0.05, 0.10) nanocrystalline powders as promising cathode materials for lithium-ion batteries. Crystalline structure, morphology, and stoichiometry of synthesized powders were characterized by XRD, FE-SEM, and AAS, respectively.

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“…The procedure to determine the average manganese valence consisted in directly transferring [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] . In this case, the blank was a solution containing only NaCH 3 COO and 1,10-phenanthroline, obtained by adding 10 mL of aqueous 10% (m/m) NaCH 3 COO and 0.1% (m/m) 1,10-phenanthroline solutions to a 50 mL volumetric flask and completing its volume with deionized water.…”

Section: Methodsmentioning

confidence: 99%

A New, Friendlier Methodology to Determine the Average Manganese Valence in LixMn2O4 Spinels Using Atomic Absorption Spectrometry and Molecular Absorption Spectrophotometry

Silva¹,

Silva²,

Biaggio³

et al. 2017

J. Braz. Chem. Soc.

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An alternative, friendlier methodology for the determination of the average manganese valence (ν) of manganese oxides (mainly pure and doped spinels) is presented. This methodology is based on the facile determination of the concentration of Mn 2+ and Fe 2+ ions by atomic absorption spectrometry (AAS) and molecular absorption spectrophotometry (MAS), respectively. Prior to this determination, the manganese oxides are reacted with an acidic solution containing Fe 2+ ions, when all Mn ν+ ions are reduced to Mn 2+. Then, the concentration of Mn 2+ ions is obtained directly by AAS, whereas that of Fe 2+ ions is obtained by MAS after their complexation with o-phenanthroline. Using this methodology, the obtained mean (n = 3) ν values for the stoichiometric oxides Mn 2 O 3 and Mn 3 O 4 are 2.98 ± 0.01 and 2.66 ± 0.01, respectively; their precision is a clear evidence of the suitability of the here-proposed methodology. Additionally, a precise mean ν value (3.46 ± 0.01; n = 3) is also obtained for the spinel Li 1.05 Mn 2 O 4 , whereas a higher ν value (3.52 and 3.53; n = 2) is obtained for the doped spinel Li 1.05 Mn 1.98 Al 0.02 O 3.98 S 0.02 , evidencing that effective doping has been indeed attained. This novel methodology is easily applicable for Mn oxides in electrode materials of many energy storage devices. Keywords IntroductionIn the last decade, the popularization of portable electronic devices has increased, leading to a growing demand for lithium ion batteries (LIBs). In this scenario, some oxides have been targeted for studying and testing as cathode materials in LIBs; the spinel lithium manganese oxide (Li x Mn 2 O 4 ) is one of these oxides.1,2 The use of this spinel is favored by factors such as the manganese abundance, non-toxicity, and low cost, as well as the possibility of insertion of two lithium ions per formula unit.3 When 0 ≤ x ≤ 1, Li 3 Therefore, the average manganese valence of doped spinels is a useful parameter because it can provide information on their effective doping and structural changes.As far as we could ascertain, the most common approach to determine the average manganese valence of manganese oxides has been the Vetter and Jaeger's method, 33 employs an acid solution of potassium iodide to reduce all Mn ions in the manganese oxides to Mn 2+ ions. In this process, iodine is formed and quantified by titration with a sodium thiosulfate solution, while Mn 2+ ions are determined by titration with an EDTA solution. Titration of iodine was also proposed by Licci et al. 34 to determine the average manganese valence in Mn-La complexes. Firstly, after the Mn-La complex is dissolved in dilute H 2 SO 4 , the Mn ions are oxidized to permanganate ions by adding an excess of solid bismuthate, followed by the addition of an iodide solution (also in excess) that converts all permanganate ions into Mn 2+ ions, yielding iodine. In a parallel step, the Mn-La complex is reacted directly with an iodide solution, also yielding iodine. In both cases, the iodine is amperometrically titrated with a thio...

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Pechini Synthesis of Nanostructured Li1.05M0.02Mn1.98O4 (M = Al3+ or Ga3+)

Cited by 4 publications

References 24 publications

PAni-coated LiFePO4 Synthesized by a Low Temperature Solvothermal Method

PAni-coated LiFePO4 Synthesized by a Low Temperature Solvothermal Method

Kinetic and Thermodynamic Studies on Synthesis of Mg-Doped LiMn2O4 Nanoparticles

A New, Friendlier Methodology to Determine the Average Manganese Valence in LixMn2O4 Spinels Using Atomic Absorption Spectrometry and Molecular Absorption Spectrophotometry

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