Multiscale Construction of Bifunctional Electrocatalysts for Long-Lifespan Rechargeable Zinc-Air Batteries

Zinc-air batteries deliver great potential as emerging energy storage systems but suffer from sluggish kinetics of the cathode oxygen redox reactions that render unsatisfactory cycling lifespan. The exploration on bifunctional electrocatalysts for oxygen reduction and evolution constitutes a key solution, where rational design strategies to integrate various active sites into a high-performance air cathode remain insufficient. Herein, a multiscale construction strategy is proposed to rationally direct the fabrication of bifunctional oxygen electrocatalysts for long-lifespan rechargeable zinc-air batteries. NiFe layered double hydroxides and cobalt coordinated framework porphyrin are selected as the active sites considering their high intrinsic activity at the molecular level, and the active sites are successively integrated on three-dimensional conductive scaffolds at mesoscale to strengthen ion transportation. Consequently, the multiscale constructed electrocatalyst exhibits excellent bifunctional performance (Delta E = 0.68 V), which is even better than that of the noble metal based benchmarks. The corresponding air cathodes endow zinc-air batteries with a reduced voltage gap of 0.74 V, a high power density of 185.0 mW cm(-2), and an ultralong lifespan of more than 2400 cycles at 5.0 mA cm(-2). This work demonstrates a feasible strategy to rationally integrate various active sites to construct multifunctional electrocatalysts for energy-related processes.