Improved reversibility of Zn anodes for rechargeable Zn-air batteries by using alkoxide and acetate ions

Abstract The irreversible formation of zinc oxide (ZnO) in Zn–air batteries is not avoidable. Because of the formation of ZnO, the battery capacity, potential, and coulombic efficiency decrease. The low electrochemical reactivity of ZnO is the main obstacle that interferes with building an electrochemically rechargeable Zn–air battery. In this work, electrolytic additives that suppress the formation of ZnO are studied. The zincate ion (Zn(OH)42−) is an intermediate ion, which transforms into ZnO in basic solutions during the discharge process. Some hydroxide ions in zincate can be replaced with alkoxide and acetate ions; this resulted in a clear improvement of the reversibility of Zn–air batteries. The modification of zincate with alkoxide/acetate suppresses its transformation into ZnO, which results in improved retention of capacity in cycle tests.