Fe3O4/N-doped carbon and MnO/N-doped carbon composites prepared from manganese ore tailings as high-performance anode materials for sodium-ion batteries

Efficient and rational use of manganese ore tailings is valuable to environmental protection and economic development. Herein, the Fe₃O₄/nitrogen-doped carbon (Fe₃O₄/C) and MnO/nitrogen-doped carbon (MnO/C) composites are synthesized by a two-step precipitation process with manganese ore tailings as the Fe and Mn resources. The sodium storage properties of the two composites as anodes were investigated in depth. The Fe₃O₄/C and MnO/C exhibit outstanding cyclic performance of 251.6 and 412.5 mAh g⁻¹ after 1000 and 500 cycles at 0.5 A g⁻¹, respectively. Even at 5.0 A g⁻¹, the Fe₃O₄/C and MnO/C still deliver specific capacities of 147.2 and 320.5 mAh g⁻¹, respectively. Compared with pure Fe₃O₄ and MnO, the improved sodium storage performance of Fe₃O₄/C and MnO/C composites can be attributed to the introduction of the N-doped carbon matrix. This carbon matrix not only mitigates the agglomeration of metal oxide nanoparticles but also enhances the electrical conductivity of the composites. Moreover, it promotes the reactivation of Fe₃O₄/C and MnO/C electrodes during repeated cycling. This work gives guidance for the high-value utilization of manganese ore tailings and the fabrication of high-performance metal oxide anodes for sodium-ion batteries.