Prism ZnO nanomaterials coated with Ca(OH)2 were prepared by direct precipitation. TEM micrographs showed that dendritic Ca(OH)2 seemed to attach on the surface of nanosized ZnO. The XRD patterns indicated that the coating was Ca(OH)2·2Zn(OH)2·2H2O. The nanosized ZnO coated with Ca(OH)2 as the anode materials were investigated by the charge–discharge cycle measurement and EIS. The combination of ZnO nanomaterials and Ca(OH)2 prevented the discharge product ZnO from dissolving in the electrolyte. Therefore, the Ca(OH)2-coated ZnO nanomaterials exhibited higher electrochemical activity than the pure nanosized ZnO, including high the discharge capacity and discharge middle voltage, low the charge middle charge voltage. Although Ca(OH)2 resulted in more difficult activation, EIS showed that the charge-transfer resistance was lower than that of the pure ZnO nanomaterials.