Rechargeable Zinc–Air Batteries with an Ultralarge Discharge Capacity per Cycle and an Ultralong Cycle Life

Abstract A conventional two‐electrode rechargeable zinc–air battery (RZAB) has two major problems: 1) opposing requirements for the oxygen reduction (ORR) and oxygen evolution (OER) reactions from the catalyst at the air cathode; and 2) zinc‐dendrite formation, hydrogen generation, and zinc corrosion at the zinc anode. To tackle these problems, a three‐electrode RZAB (T‐RZAB) including a hydrophobic discharge cathode, a hydrophilic charge cathode, and a zinc‐free anode is developed. The decoupled cathodes enable fast ORR and OER kinetics, and avoid oxidization of the ORR catalyst. The zinc‐free anode using tin‐coated copper foam that induces the growth of (002) Zn planes, suppresses hydrogen evolution, and prevents Zn corrosion. As a result, the T‐RZABs have a high discharge capacity per cycle of 800 mAh cm −2 , a low voltage gap between the discharge/charge platforms of 0.66 V, and an ultralong cycle life of 5220 h at a current density of 10 mA cm −2 . A large T‐RZAB with a discharge capacity of 10 Ah per cycle with no obvious degradation after cycling for 1000 h is developed. Finally, a T‐RZAB pack that has an energy density of 151.8 Wh kg −1 and a low cost of 46.7 US dollars kWh −1 is assembled.