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

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.

Automated summary

A three-electrode rechargeable zinc-air battery (T-RZAB) with decoupled cathodes and a zinc-free anode is developed to solve the problems of opposing requirements for oxygen reduction/evolution reactions and zinc corrosion. The T-RZAB exhibits a high discharge capacity per cycle, low voltage gap, and ultralong cycle life. A large T-RZAB with no significant degradation after cycling for 1000 hours is also achieved. Moreover, a T-RZAB pack with high energy density and low cost is assembled.