PURPOSE: To enable a long period operation of a secondary battery while securing the smoothness of the surface of an electrode by preparing the electrode from a conductive plastic into which a dendrite-suppressing agent is kneaded.

CONSTITUTION: A conductive plastic into which a dendrite-suppressing agent is kneaded, is used as an electrode. For instance, after approximately 0.1∼3% of tetrabutylammonium bromide is added to and kneaded with an electrode material consisting of 65wt% of polyethylene and 35wt% of conductive carbon black, the mixture is subjected to heat press at 180°C with a pressure of 130kg/cm2 for five minutes so as to form a thin plate-like electrode 6. In a secondary battery constituted by using the thin electrode 6 and a cathodic electrolyte consisting of 3mol/l zinc bromide solution, charging of the battery is performed by varying current density until the quantity of charging electricity reaches 360mAH/cm2. As a result, zinc was homogeneously electrodeposited over the surface of the electrode 6, and the smoothness of the electrodeposition layer has been affirmed to be excellent. In addition, when a cycle operation of 20mA/ cm2.8Hr was performed with the electrode 6, the operation could be stably performed over a long period.