The invention belongs to the technical field of materials, and relates to a preparation method of a fluorinion-induced
manganese oxide composite material and application of the fluorinion-induced
manganese oxide composite material as a positive
electrode material in an aqueous
magnesium ion capacitor. The preparation method comprises the following steps: firstly, preparing a MnO2 precursor from a positive
electrode through a hydrothermal method, and annealing to obtain a pure-phase MnO2
nanoflower structure; the preparation method comprises the following steps: preparing MnO2 nanoflowers, adding the prepared MnO2 nanoflowers into
polyethylene glycol, adding
manganese chloride,
potassium fluoride and
polyvinylpyrrolidone, carrying out
ultrasonic dispersion for 30 minutes, continuously stirring for 1 hour, and transferring the obtained
mixed solution into a Teflon reaction kettle for
hydrothermal reaction to obtain the MnO2 / Mn2O3 / KMnF3
composite material. The composite material is used as a positive
electrode and
activated carbon is used as a negative electrode to assemble a water-based
magnesium ion capacitor device, and the water-based
magnesium ion capacitor device can reach relatively high specific
capacitance after an electrochemical test. According to the invention, a hydrothermal method is adopted for synthesis, the process is simple, the material cost is low, and the material is non-toxic and harmless, so that the capacitor has high practical application value and is expected to become a novel green
energy storage device.