Abstract: Provided is an electrolyte including a bromine complexing agent and a metal ion additive. The electrolyte is prepared by inputting zinc bromide (ZnBr2) salt, a bromine complexing agent, and a metal ion additive containing Mn to DI water. The bromine complexing agent prevents a crossover phenomenon by capturing bromine to alleviate self-discharge at a positive electrode, and the metal ion additive inhibits the formation of zinc dendrites on a negative electrode through an electrostatic shielding effect. Accordingly, battery performance may be improved by a synergistic effect generated in a positive electrode and a negative electrode by the bromine complexing agent and the metal ion additive.