Advanced Zn-air batteries based on efficient and durable perovskite/dual-doped graphene bifunctional oxygen catalysts

Abstract

Rechargeable Zn-air batteries (ZABs) are regarded as promising energy storage devices due to their high energy and power density, high safety and cost-effectiveness. Nevertheless, the practical application has been hampered by the sluggish kinetics of the oxygen reaction during the discharge and charge processes, respectively. Herein, La0.75Sr0.25 Fe0.5Mn0.5O3 (LSFMO) nanoparticles with a modified coprecipitation method possess high intrinsic activities. More importantly, the synergic covalent coupling between N/S dual-doped reduced graphene (NS-RGO) and LSFMO greatly improves the ORR and OER capabilities of novel perovskite/dual-doped graphene hybrid material (LSFMO@NS-RGO). The oxygen reduction reaction (ORR) activity (E1/2 of 0.806 V and n of 3.66) and oxygen evolution reaction (OER) activity (the Ej=10 of 1.672 V and overpotential of 442 mV) of LSFMO@NS-RGO are equivalent to the advanced Pt/C catalyst and RuO2 catalyst, respectively, thereby leading to excellent bifunctional property (ΔE = 0.86 V). Rechargeable ZABs deliver a fairly small charge-discharge voltage polarization (0.72 V). Besides, a rechargeable ZAB with flowing-electrolyte is constructed, which reveals considerably high reversibility and stability over 80 h, much improved over rechargeable ZAB in static electrolyte system. Such excellent results demonstrate that LSFMO@NS-RGO represents a new class of promising bifunctional catalysts for rechargeable ZABs.