The Study On Preparing Particle Manganese Dioxide And LiMn₂O₄from Manganese Anode Slag

Spinel LiMn2O4is widely used as cathode in lithium-ion battery due to its advantages of cheap cost, non-toxic, resistant to overcharge, and so on. In this paper, orange peel was used as reductant for reductive leaching of manganese anode slag. Then, the electrolysis method was applied to obtain micrograined manganese dioxide. This produced precusor was treated as the raw material for the next process of preparing LiMn2O4cathode.Manganese anode slag originated from analysis has not been reasonably employed owing to its complexed composition, although it was featured as manganese-rich resources. In this study, Taking orange peel as reductant, sulfuric acid as leaching solvent, the manganese anode slag was prepared. The leaching prcoss was studied systematac ially. The results showed that the leaching ratio of Mn reached96%, left behind almost all of Pb in the forms of precipitation under the following conditions:the leaching temperature is at80℃, and the leaching time is2h. The ratio of liquid to solid is4:1, orange peel to slag1:5, and acid to material1.2:1. This method proved to be effective.Particle electrolytic manganese dioxide was one kind of excellent precursor for the preparation of LiMn2O4cathode. The electrolysis method was adopted to produce this material. The effects of current density, temperature and concentration of sulfuric acid on the cell voltage, current efficiency and morphology of MnO2were investigated. The experiments verified that the optimized conditions were as follows:the current density was30A·dm-2, The temperature is at30℃, The concentration of manganese sulfate was0.8mol/L, and the concentration of sulfuric acid was2.5mol·L-1. The corresponding current efficiency reached47%. The prepared MnO2at this optimum condition has a narrow particle size distribution, and the morphology of uniform spherical-likeness, which is an ideal particle manganese dioxide.Taking electrolytic manganese dioxide as manganese sources, the LiMn2O4cathode was prepared by roasting at the temperature of800℃ for24h. The effect of different Li/Mn ratio on the performance of LiMn2O4was studied, and the influence of Pb doping on the LiMn2O4was analyzed. In contrast with the different LiMn2O4synthetized from different electrolytic manganese dioxide, the results showed that the best pot of the Li/Mn ratio was1.05:1.95. The capacity retention rate was92.5%. It was found that the electrochemical performance of the Li1.05Mn1.95-xPbxO4cathode increased to a certain extent when x=0.02. LiMn2O4synthesized from the particle electrolytic manganese dioxide has a unique advantage of fine particles and uniform morphology. The initial discharge capacity was119mAh·g-1at0.1C, and remained109.6mAh·g-1after50cycles at1.0C rate.