Cu-based cathodes in aqueous batteries become very attractive in view of high theoretical capacity, moderate operation voltage and rich reserves of raw materials. However, their applications are obstructed by serious side reactions. The side reaction mainly arises from the spontaneous formation of Cu2O, which occupies the electrode surface and lowers the reaction reversibility. Here, Na2EDTA is introduced to address these issues. Both experimental results and theoretical calculations indicate that the Na2EDTA reshapes the solvation structure of Cu2+ and modifies the electrode/electrolyte interface. Therefore, the redox potential of Cu2+/Cu2O is reduced and the surface of Cu is protected from H2O, thereby inhibiting the formation of Cu2O. Meanwhile, the change in the solvation structure reduces the electrostatic repulsion between Cu2+ and the cathode, leading to high local concentration and benefiting uniform deposition. The results shed light on the applications of rechargeable Cu-based batteries.