Enabling High-Power-Density Zn-Air Batteries via Oxygen Trapping in Lotus-Effect-Inspired Hydrophobic Air Electrodes

The sluggish oxygen diffusion kinetics at the triple-phase boundary of the air cathode significantly limit the optimal power output of Zn-air batteries (ZABs). Inspired by the "lotus effect", this study developed a bifunctional electrocatalyst, Co─NCNTs, featuring a lotus leaf-like structure, and constructed a 3D hydrophobic architecture to expand the triple-phase boundaries. Consequently, the hydrophobic Co─NCNTs electrode (contact angle >140°) demonstrated enhanced oxygen adsorption on the air cathode surface compared to the hydrophilic Co─NC electrode (contact angle <70°). The assembled ZABs incorporating the lotus-effect-inspired bionic Co─NCNTs achieved a remarkable power density of 341 mW cm^-2, nearly double that of the hydrophilic Co─NC-based battery (178 mW cm^-2), and exhibited exceptional cycling stability, operating continuously for 700 h at a current density of 10 mA cm^-2. This work highlights the efficacy of hydrophobic interface engineering in improving the reaction kinetics of air cathodes in ZABs through bionic design, offering a promising strategy for enhancing the power density of oxygen-involved energy storage systems.