Research On Preparation Of High Purity Manganic Manganous Oxide By Liquid Phase Method

Trimanganese tetroxide, an important inorganic material, was widely uesd in catalysis, magnetic materials, electrochemical, air purification, etc. With the rise of green energy automobile in recent years, the charateristics requirements of lithium-ion batteries have been gradually improved. LiMn2O4, an anode material of lithium-ion battery, its purity and particle size had great influence on charge-discharge performance after repeated use of lithium-ion batteries. And the trimanganese tetroxide is a key material to prepare LiMn2O4. Hence, it is important to prepare Mn₃O₄ with high purity and a certain particle size.The study was used manganese sulfate and sodium hydroxide to preparation of high purity Mn₃O₄ by liquid phase oxidation method. And the influence of different conditions on the purity, particle morphology of the product had been discussed.Orthogonal and single factor experiments had been employed to investigate the effects of the concentration of MnSO4, alkali manganese ratio, reaction temperature, reaction time, stirring speed, air flow, drying time and drying temperature on the purity of Mn₃O₄. The results indicated that manganese sulfate concentration 0.40 mol/L, alkali manganese ratio 2, stirring speed 300 r/min, air flow 13.33 L/min, reaction temperature 65℃, reaction time 7h, drying temperature 110℃, drying time 3 h. Under these conditions, manganese content of product reached 71.51%, and the particle size was 1.83μm.Then series of experiments had been employed to investigate the effects of sulfate concentration, alkali manganese ratio, reaction temperature, reaction time, stirring speed, air flow ageing time on the particle size of Mn₃O₄. Results also showed that the optimum conditions with larger particle size were as follow: manganese sulfate concentration 0.40 mol/L, alkali manganese ratio 2, stirring speed 200 r/min, air flow 13.33 L/min, reaction temperature 80 ℃, reaction time 8 h, added 5g seed, ageing time chose 24 h. The particle size of Mn₃O₄ was 5.41 μm, and manganese content of product was 71.04%.The additives of ethanol, ethylene glycol, glycerin, triethanolamine, sodium acetate, sodium oxalic acid, tartaric acid and EDTA-2Na on the influence of particle size, manganese oxide content and morphology were investigated. The results indicated that the hydroxyl and carboxyl could spread the manganese oxide particles, and the increase of number of hydroxyl or carboxyl could improve the dispersion strengthening. Ethanol could effectively reduce the content of MnSO4 which encapsulated Mn₃O₄. And because of little effects of Hydration and hydrogen bonding, agglomeration could been reduced, then improved the purity of the Mn₃O₄. The technological conditions were determined as follows:manganese sulfate concentration 0.40 mol/L, alkali manganese molar ratio 2, stirring speed 200 r/min, air flow 13.33 L/min, reaction temperature 80 ℃, reaction time 8 h, added 5g seed, ageing time chose 24 h. The particle size of trimanganese tetroxide was 6.35 μm, and manganese content of product was 71.82%. XRD analysis showed the product was Mn₃O₄.