The invention relates to the field of batteries and particularly discloses a cathode piece. The cathode piece comprises a current collector, a silicon film layer, a buffer layer and a second active material body, wherein the buffer layer is located between the current collector and the silicon film layer; crevices are formed in the silicon film layer and the buffer layer and are filled with the second active material body covering the silicon film layer; and the second active material body contains graphite and polyimide. The buffer layer is arranged between the current collector and the silicon film layer, and the second active material body permeates the crevices to form a tightly linked integer through the current collector, the buffer layer and the silicon film layer, so that the adhesive force between the silicon film layer and the current collector is effectively strengthened, and the phenomenon of falling between the silicon film layer and the current collector is avoided. Besides, the silicon film layer is located between the buffer layer and the second active material body, so that the problem of pulverization of silicon is effectively inhibited. The invention further discloses a preparation method of the cathode piece and a battery.