Additive-Free Gas Diffusion Electrodes with Bimetallic and Trimetallic Catalysts for Zinc-Air Batteries

The gas diffusion electrode (GDE) in a zinc-air battery (ZAB) plays a critical role in determining battery performance by allowing oxygen to transfer from the air and undergo electrochemical reactions. However, traditional GDE approaches overlook the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as well as catalyst poisoning and corrosion, which reduce battery capacity and lifespan. To overcome these challenges, here we propose the synthesis of bimetallic and trimetallic catalysts for use in GDEs in rechargeable ZABs by electrodeposition. We evaluated additive-free catalyst layers with bimetallic MnxNi1–xO4 (MnNi) and trimetallic MnNixMyO4 (MnNiM, such as MnNiFe, MnNiCo, and MnNiZn) catalysts for ZABs. MnNixMyO4 trimetallic catalysts exhibit improved OER/ORR activities, while the MnNiZn catalyst with a molar Ni/Zn ratio of 1:1 in the precursor shows excellent stability for 400 h during charge–discharge cycles in 6 M KOH electrolyte. The electrode exhibits approximately 65.6% discharge/charge efficiency at a 5 mA cm–2 current density, indicating that the MnNiZn catalyst is a promising candidate for high-performance ZABs.