Microscale-decoupled charge-discharge reaction sites for an air electrode with abundant triple-phase boundary and enhanced cycle stability of Zn-Air batteries

Abstract

Decreasing the charge-discharge voltage gap and increasing the cycling stability is pivotal but challenging for the practical application of rechargeable Zn-air battery (ZAB). Until now, many efforts have been paid in the electrocatalyst development for the air electrode, but few works have been done on the electrode structure design which is quite import for the battery performance. Herein, we design a decoupled air electrode by integrating a hydrophilic mesh active for oxygen evolution reaction (OER) with a hydrophobic layer active for oxygen reduction reaction (ORR). The decoupled air electrode could separate the OER and ORR sites at microscale, which could alleviate the oxidative corrosion of the ORR layer along cycling. Meanwhile, it also shows adjustable contact angle by fancily changing the texture of the mesh, which enables the optimal hydrophilicity towards abundant triple phase boundary for superior discharge performance. The ZAB based on the decoupled air electrode exhibits a small initial voltage gap of 0.75 V at 10 mA cm−2, and it was stably cycled for 240 h. This work provides a feasible strategy to simultaneously accelerate the electrochemical reaction and improve the electrode stability, and it could be inspiring for other multiphase reaction involved devices.