Preparation method of porous graphite paper

The invention discloses a preparation method of porous graphite paper. The preparation method comprises the following steps: (1) cutting the graphite paper to be rectangular, cleaning the graphite paper, carrying out drying, and placing the graphite paper into a polytetrafluoroethylene bottle; (2) preparing a KMnO4 solution; (3) adding the KMnO4 solution into the polytetrafluoroethylene bottle filled with the graphite paper in the step (1), then, placing the bottle into a stainless steel hydrothermal reactor, and carrying out sealing for a reaction; (4) naturally cooling the reactor to the room temperature, washing the reacted graphite paper by using deionized water, and carrying out drying to obtain an MnOx/GP electrode; and (5) standing the MnOx/GP electrode obtained in the step (4) intoan HCL solution until manganese oxides on the surface of the graphite paper are completely dissolved, then, flushing the graphite paper by using deionized water, and carrying out drying to obtain a porous graphite paper elec