Study on the properties of the MgCO₃@2Mn_1-xM_xCO₃ carbonate composite material as a cathode electrode in the aqueous zinc-ion battery and the effect of Ag ion doping at the manganese site

With the international background of advocating green environmental protection and sustainable development, the aqueous zinc ion battery has attracted researchers' attention because of its many advantages. The application of a manganese-based material as a positive electrode in the aqueous zinc ion battery has broad development prospect. In this paper, the composite materials of manganese carbonate and magnesium carbonate were synthesized by the hydrothermal method. Metal ions were doped at the manganese site of the composite materials to synthesize MgCO3@2Mn(1-x)M(x)CO(3) materials. By comparing the electrochemical performance test results, it can be seen that the MgCO3@2Mn(0.995)Ag(0.005)CO(3) material showed better magnification performance and its capacity can reach 282.6 mAh/g at 50 mA/g current density. Moreover, its electrochemical performance is also better than that of other doped materials. Through the scanning electron microscopy image analysis of the material, it can be seen that the material is mainly in a cubic structure of different sizes and the small cube structures are crosslinked together to form a sheet structure, which can further increase the closeness of the particle connection. By energy dispersive spectroscopy and x-ray photoelectron spectroscopy analysis, it can be found that the corresponding valence states of Mn, C, O, and Mg elements in the material are consistent with those in the MgCO3@2Mn(0.995)Ag(0.005)CO(3) material. In the XRD test, the crystallinity of the material is good, and no obvious impurity peak is found.