Because of the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), binary ruthenium-tin oxides synthesized by a hydrothermal method with postannealing at 450 °C for 2 h are first proposed as bifunctional catalysts for these two reactions on the air electrode of rechargeable zinc-air batteries. The binary Ru-Sn oxides in various compositions show the typical oxide solid solution in the rutile phase. Among all binary Ru-Sn oxides, RuSn73 (70 atom % RuO and 30 atom % SnO) and RuSn37 (30 atom % RuO and 70 atom % SnO) show the highest catalytic activities toward the OER and ORR, respectively. Consequently, a novel design of the air electrode consisting of a RuSn37 coating on the carbon paper and a Ti mesh coated with RuSn73 (denoted RuSn(37-C|73-Ti)) is proposed to possess the optimal charge-discharge performances. A unique cell employing such an air electrode has been demonstrated to exhibit a very low charge-discharge cell voltage gap of 0.75 V at 10 mA cm. This cell with a peak power density of 120 mW cm at the current density of 235 mA cm also shows an outstanding charge-discharge stability over 80 h. This cell also exhibits an exceptionally high charge rate capability at 150 mA cm with a low charging voltage of 2.0 V.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.