Controllable Urchin‐Like NiCo₂S₄ Microsphere Synergized with Sulfur‐Doped Graphene as Bifunctional Catalyst for Superior Rechargeable Zn–Air Battery

Abstract

Abstract Rechargeable zinc–air batteries (ZnABs) are attracting great interest due to their high theoretical specific energy, safety, and economic viability. However, their performance and large‐scale practical applications are largely limited by poor durability and high overpotential on the air‐cathode due to the slow kinetics of the oxygen reduction and evolution reactions (ORR/OER). Therefore, it is highly desired to exploit an ideal bifunctional catalyst to endow the obtained ZnABs with excellent ORR/OER catalytic performances. Herein, a new nonprecious‐metal bifunctional catalyst of urchin‐like NiCo 2 S 4 microsphere synergized with sulfur‐doped graphene nanosheets (S‐GNS/NiCo 2 S 4 ) is controllably designed and synthesized by simply tailoring the structure and electronic arrangement, which endow the as‐prepared catalyst with excellent electroactivity and long‐term durability toward ORR and OER. Importantly, ZnABs constructed by this outstanding catalyst exhibit high power density, small charge/discharge voltage gap, and excellent cycle stability, notably outperforming the more costly commercial Pt/C + Ir/C mixture catalyst. These excellent electrocatalytic performances together with the simplicity of the synthetic method, make the urchin‐like NiCo 2 S 4 microsphere/S‐GNS hybrid nanostructure exhibit great promise as a superior air‐cathode catalyst for high‐performance rechargeable ZnABs.