Rechargeable zinc-air batteries with an ultra-large discharge capacity per cycle and an ultra-long 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. (2) Zinc dendrite formation, hydrogen generation and zinc corrosion at the zinc anode. To tackle these problems, we have developed a three-electrode RZAB (T-RZAB) including a hydrophobic discharge cathode, a hydrophilic charge cathode, and a zinc-free anode. 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 discharge/charge platforms of 0.66V, and an ultra-long cycle life of 5220 hours at a current density of 10mA cm-2 . We have developed a large T-RZAB which has a discharge capacity of 10 ampere-hours per cycle with no obvious degradation after cycling for 1000 hours. Finally, we assembled a T-RZAB pack that had an energy density of 151.8 watt-hours per kilogram and a low cost of 46.7 US dollars per kilowatt-hour. This article is protected by copyright. All rights reserved.