A novel layered cobalt oxide Ba2Co9O14 as an efficient and durable bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries.

• A novel layered cobalt oxide Ba 2 Co 9 O 14 is developed as a bifunctional oxygen catalyst. • Ba 2 Co 9 O 14 based ZAB shows an excellent maximum power density of 166 mW cm−2 with good cycling stability. • Ball-milling treatment exhibits increased specific surface area and enlarged pore size. • Ball-milling benefits the enhancement of the ZAB. In this work, a layered cobalt oxide Ba 2 Co 9 O 14 (BCO), belongs to a Ba n+1 Co n O 3n+3 (Co8O8) family composed by alternating CdI 2 based layers (Co8O8) with n (111) perovskite blocks (Ba n+1 Co n O 3n+3), has been developed as a potential bifunctional oxygen electrocatalyst candidate for efficient and durable rechargeable zinc-air battery (ZAB) application. Because of the greatly increased the specific surface area caused by ball-milling, the as-milled BCO material exhibits strongly enhanced bifunctional electrocatalytic activity towards oxygen reduction and oxygen evolution reaction in alkaline medium. Moreover, the assembled BCO-based ZAB yields an effectively improved maximum output power density of 166 mW cm−2, a considerable specific capacity of 789 mAh g −1, and excellent charge-discharge cycle stability of over 250 h at 10 mA cm−2 with over 1500 cycles. A layered cobalt oxide Ba 2 Co 9 O 14 (BCO) is a promising bifunctional oxygen electrocatalyst for efficient and robust rechargeable zinc-air battery, which is further enhanced by the ball-milling treatment because of the formation of more active reaction sites. [Display omitted] [ABSTRACT FROM AUTHOR]