A long life and high efficient rechargeable hybrid zinc-air/Co3O4 battery with stable high working voltage

Rechargeable hybrid zinc battery has a higher working voltage and a higher energy density than the conventional zinc-air battery and is considered as one of the potential candidates for the next generation of secondary batteries. Herein, we demonstrate a novel rechargeable hybrid zinc battery using Co3O4 nanowire arrays grown directly on nickel foam current collector as electro-catalysts of a cathode, coupled with a steel-foil anode current collector in 6 M KOH aqueous solution electrolyte with adding ZnO. The synthesized Co3O4 nanowire arrays with a unique open 3D structure ensure the effective utilization of the catalytic sites and rapid diffusion of oxygen, thus providing excellent electrochemical performances. The resultant battery can deliver electrochemical energy through the redox reactions of cobalt oxides in the Zn-Co3O4 battery and ORR/OER in the Zn-air battery. The hybrid zinc battery cycled steadily up to 2200 cycles (over 977 h) with the highest Coulombic efficiency of 92.8%. Almost every cycle exhibits a single flat discharge voltage plateau at around 1.65 V. These results provide critical advances in developing a robust rechargeable hybrid zinc battery for large-scale applications.