Efficient recovery and utilization of electrolytic manganese anode mud- preparation of high-performance Li1.2Ni0.2Mn0.6O2 cathode material for lithium-ion batteries

The booming electrolytic manganese industry has brought a huge amount of electrolytic manganese anode mud (EMAM). The management and value-added recovery of EMAM were very important for environmental improvement and economic benefits. In this study, EMAM is used as a cost-effective raw material. Firstly, the manganese-containing solution was obtained by reducing acid leaching with EMAM. Then, Li1.2Ni0.2Mn0.6O2 (Z-LNMO) cathode materials were prepared from a manganese-containing solution by co-precipitation process. Finally, to enhance the performance of the Z-LNMO materials, surfactants (C12H25SO4Na, C10H14N2Na2O8, C18H29NaO3S, C19H42BrN) were introduced in the preparation of precursor materials to obtain the material with higher crystallinity. ICP results showed that S/Fe ions of EMAM were retained in Z-LNMO materials. Moreover, the Z-LNMO sample shows a stoichiometric similar element content to Li1.2Ni0.18Fe0.02Mn0.6O1.96S0.04. EDS results show that S/Fe ions were uniformly distributed in Z-LNMO materials. The shift of XRD peak further indicates that the use of EMAM waste is expected to directly obtain S/Fe ions doped lithium-rich manganese-based cathode materials. The first-principle calculation shows that the S/Fe ions as the doping source make the transfer of excited electrons from the valence band to the conduction band easier, thereby enhancing the conductivity of the materials. The CV curve and differential capacity (dQ/dV) curve show that the Z-LNMO material prepared by EMAM inhibits the excessive oxidation of Li2MnO3 to a certain extent, thus providing excellent reversible capacity and stabilizing the material structure. Electrochemical evaluation reveals that the Z-LNMO materials prepared with the EMAM exhibit superior cycling stability (112% after 100 cycles at 0.1C). Moreover, the introduction of C10H14N2Na2O8 (EDTA-2Na) and C12H25SO4Na (SDS) in the preparation of precursor materials can improve the first discharge-specific capacity and stability of materials by modifying the morphology of precursor materials (refine particles). Among them, the materials modified by EDTA-2Na show the best performance, and the particle size is about 200 nm. Compared with the original materials, the improved first discharge-specific capacity (218.6 mAh g−1 at 0.1C) and capacity retention (245.8 mAh g−1 after 100 cycles) of the materials modified with EDTA-2Na were improved. The EIS results also confirm that the introduction of EDTA-2Na effectively decreases the charge transfer resistance and facilitates the Li diffusion of the as-prepared cathode materials. This work confirmed the possibility of extracting manganese from EMAM to prepare lithium-rich manganese-based cathode materials, and provided a new promising way for the efficient value-added utilization of EMAM.