Carbon dot modified Mn2O3 porous spheres as cathode materials for high performance zinc ion batteries

Manganese oxide is a promising material due to its low cost, abundant reserves, and environmental friendliness. However, low cycling performance has been restricting the manganese oxide cathode materials on the road to commercialization. In this paper, Mn₂O₃ microspheres with a porous structure are prepared by hydrothermal process and then compounded with low dimensional and small-scale carbon dots (CDs), and the obtained Mn₂O₃/CDs materials are used to assemble aqueous zinc ion batteries. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) are used to characterize its structure and morphology, which prove that the composite with CDs do not change the structure of the original material. The morphology of microspheres can increase the surface area of electrolyte-electrode interface, which is beneficial to ion embedding into cathode materials. Compared with pure Mn₂O₃, the composite with CDs content of 3% (MC3) has the best electrochemical performance (the discharge specific capacity is 252.7 mAh·g⁻¹ at 0.1 A g⁻¹). Moreover, the reversible capacity of the Mn₂O₃/CDs composites is improved due to the inhibition of the dissolution of Mn by the highly conductive CDs. The specific discharge capacity of the Mn₂O₃/CDs composites after 300 cycles is 102.8 mAh·g⁻¹, which is 2.3 times higher than that of the pure Mn₂O₃.