Highly active LMO/Ni(Fe)-LDH bifunctional gas-diffusion electrode with bilayer design

Rechargeable zinc–air batteries (RZABs) possess considerable potential toward next-generation energy storage. The performance of RZABs mainly hinges on the air electrode. However, traditional approaches for bifunctional air electrodes overlook the distinct reaction field requirements for oxygen redox reactions, which leads sluggish reaction kinetics and a limited lifespan. To overcome these challenges, here we propose a bilayer gas diffusion electrode (GDE) with well-balanced hydrophobicity/hydrophilicity, which is designed to extend the reactive interface into the different reaction fields of the catalytic layers. In this configuration, the LaMnO 3+ δ (LMO) catalyst for oxygen reduction is positioned on the gas diffusion layer (air) side, while the Ni(Fe)-layered double hydroxide (LDH) catalyst for oxygen evolution is placed on the electrolyte side. The bilayer GDE serves as a highly efficient bifunctional electrode, exhibiting a minimal potential difference of 0.58 V at 10 mA cm −2 and 0.69 V at 100 mA cm −2 between the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Its mechanical and electrochemical stability ensures prolonged operation at high current densities without degradation. When implemented in ZABs, bilayer GDE based RZAB achieves a low charge/discharge voltage gap of 0.69 V at 10 mA cm −2 and a long-cycling durability (over 300 h). • Bilayer design based on oxygen redox reaction fields. • The zinc–air full cell shows a small voltage gap of 0.69 V at 10 mA cm −2 . • The balanced hydrophobicity and hydrophilicity suppress electrode degradation.