Fe0.96S/Co8FeS8 nanoparticles co-embedded in porous N, S codoped carbon with enhanced bifunctional electrocatalystic activities for all-solid-state Zn-air batteries

Simultaneous acquisition of satisfactory bifunctional activities toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for single transition metal sulfides is challenging, which greatly restrict their applications as cathode catalysts in the rechargeable Zn-air batteries (ZABs). Herein, Fe0.96S/Co8FeS8 nanoparticles co-embedded in 3D porous N, S codoped carbon (Fe1Co1Sx@NSPC) were fabricated with regulated ratio of iron to cobalt. Compared with single iron sulfide catalyst (Fe0.96[email protected]), the obtained Fe1Co1Sx@NSPC exhibits enhanced activities in both ORR and OER, whose half-wave potential and overpotential (at 10 mA cm−2) are 0.82 V, 0.39 V. The improved electrocatalytic activities are believed to be from the synergistic effects between the binary sulfides and the N, S co-doping and the 3D porous structures. As expected, the home-made aqueous ZAB based on Fe1Co1Sx@NSPC exhibits a high peak power density (159 mW cm−2), large specific capacity (807 mAh g−1) and a long-term charge/discharge cycling stability over 378 cycles at about 852 mV. Moreover, the self-made all-solid-state button ZAB based on Fe1Co1Sx@NSPC shows a high peak power density (71 mW cm−2) and a well maintained cycle life at about 841 mV over 100 charge/discharge cycles.