A Highly Reversible Sn‐Air Battery Possessing the Ultra‐Low Charging Potential with the Assistance of Light

Abstract Aqueous Sn‐air batteries are attracting a great deal of interest in recent years due to the ultra‐high safety, low cost, dendrite‐free and highly reversible Sn anode. However, the slurry oxygen reduction/evolution reaction (ORR/OER) kinetics on the air cathodes seriously affect the Sn‐air battery performances. Although various advanced catalysts have been developed, the charge overpotentials (~1000 mV) of these Sn‐air batteries are still not satisfactory. Herein, iron oxide (Fe 2 O 3 ) modified titanium dioxide (TiO 2 ) nanorods with heterogeneous structure are firstly synthesized on Ti mesh (Fe 2 O 3 @TiO 2 /Ti), and the obtained Fe 2 O 3 @TiO 2 /Ti films are further applied as catalytic electrodes for Sn‐air batteries. The core–shell heterogeneous structure of Fe 2 O 3 @TiO 2 /Ti can effectively facilitate the conversion of electrochemical intermediates and separation of photo‐excited electrons and holes to activate oxygen‐related reaction processes. Density functional theory (DFT) and experimental results also confirm that Fe 2 O 3 @TiO 2 /Ti can not only act as the electrocatalysts to improve ORR/OER properties, but also exhibit the superior photo‐catalytic activity to promote charging kinetics. Hence, the Fe 2 O 3 @TiO 2 /Ti‐based Sn‐air batteries show ultra‐low overpotential of ~40 mV, excellent rate capability and good cycling stability under light irradiation. This work will shed light on rational photo‐assisted catalytic cathode design for new‐type metal‐air batteries.