Cobalt‐Doped Tungsten Sulfides as Stable and Efficient Air Electrodes for Rechargeable Zinc‐Air Batteries

Abstract Stable and efficient air electrode are significantly important for the industrial applications of rechargeable zinc‐air batteries (ZABs). In this work, we introduce approximately 1 at % cobalt to tungsten sulfides nanosheets (Co−WS 2 ) to create a bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A boosted ORR activity with half‐wave potential of 840 mV vs. RHE is achieved for Co−WS 2 compared to that of WS 2 (776 mV vs. RHE). Meanwhile, the overpotential for delivering 10 mA cm −2 in OER catalysis is decreased from 492 to 303 mV after doping with Co atoms. The excellent ORR and OER activities are ascribed to the presence of Co 2+ and Co 3+ species in Co−WS 2 , enabling OOH* intermediate formation and strong binding ability to O 2 , respectively. The assembled liquid rechargeable ZAB from Co−WS 2 exhibits a threefold higher power density than commercial Pt/C−IrO 2 ; moreover, a stable discharge‐charge performance (100 cycles) is recorded. Finally, the fabricated all‐solid‐sate ZAB exhibits a reasonably high power density of 58 mW cm −2 and good stability, implying the potential application of Co−WS 2 as an air electrode for rechargeable ZABs.