Preparation And Application Of Heavy Chemical Manganese Dioxide

Along with the rapid development of energy materials and the technology ofelectronic industry. Manganese oxides have attracted much attention for ascended to thefield of high technology materials, manganese of Industrial products are widely used inelectronics, energy, chemical, steel, pharmaceutical and other industries. Manganesedioxide is one of the most important inorganic chemical raw materials and mainly usedin battery industry. The demand for this product is increasing with the rapiddevelopment of battery industry, especially the demand for high quality manganesedioxide. At present, the properties of CMD approach to EMD, CMD has low productcost and CMD has tremendous development potential. However, the low apparentdensity of CMD, which limits its developing. Therefore, the study of preparation ofMnO2with high apparent density and its application has become the hot topic ofresearch.In this study, the worldwide development of MnO2in recent years was summarizedand analyzed, aimed at defect of CMD such as low apparent density, high densitymanganese carbonate was prepared by using manganese sulfate and ammoniumbicarbonate as starting materials. Crude MnO2was prepared by through pyrolysis ofMnCO3, and after that high apparent density of MnO2was prepared by the densificationprocess of Crude MnO2. The spinel LiMn2O4cathode materials were synthesized bysolid-state reaction and use CMD as Mn source. The structure，ingredient and surfacemorphology of relevant materials were investigated by herm gravimetric differentialthermal analyzer， chemical titration， X-ray diffraction and scanning electronmicroscope.Manganese carbonate was prepared by chemical precipitation of crystal seedcontrol; all the materials are pure calcite crystalloid. The reaction temperature is30℃,seed crystal consumption is20%, the concentration of ammonium bicarbonate is2mol/Land the dropping time of reactants is4.5h，the tap density of manganese carbonateprepared under these conditions reaches2.3g/cm3and the preparation method has goodreproducibility. The dense manganese carbonate was pyrolysised12h at350℃，thecontent of MnO2in the thermolysis product is78.43%. When the raw material areuniform mixture，the tap density of MnO2reach2.1g/cm3can be prepared under thereaction time is3hours, the percentage of new generating of MnO2by NaClO3oxidation in crude MnO2is20%，and the ratio of liquid to solid is3:1.Spinel liMn2O4materials were synthesized bysolid state reactions and use CMDand EMD as Mn source, all the synthesized materials are pure spinel phase withuniform size and no serious aggregation can be observed. When cycled at room temperature for50times at the current of0.2C，the capacity retention of LiMn2O4which use CMD as Mn source were91.34%,82.04%,79.05%，that are higher than78.83%use EMD as Mn source；and at55℃the capacity retention were91.23%、81.12%、78.23%，that also are higher than72.8%use EMD as Mn source. The dischargespecific capacity of LiMn2O4which use EMD as Mn source was108.63mAh/g at thecharge-discharge current of0.2C at room temperature are higher than that78.71mAh/g，94.21mAh/g which use CMD with low apparent density as Mn source，but thedischarge specific capacity of LiMn2O4which use CMD with high apparent density asMn source was109.37mAh/g are higher than that which use EMD as Mn source. Thedischarge specific capacity of LiMn2O4which use CMD with high apparent density asMn source at the charge-discharge current of0.5C is lower than that use EMD as Mnsource，but when the current reaches1C，2C and3C，the discharge specific capacityBecome higher than that use EMD as Mn source.