S-doped CoMn2O4 with more high valence metallic cations and oxygen defects for zinc-air batteries

The strategy of introducing heteroatom sulfur (S) in the cobalt manganese spinel oxides (CoMn2O4) is employed to boost the bifunctional electrocatalyst. The optimized sample of S-CoMn2O4 shows overpotentials shifts of 60 mV at 10 mA cm(-2) for the oxygen evolution reaction (OER) and 40 mV for the oxygen reduction reaction (ORR). X-ray photoelectron spectroscopy results reveal that the S-doping can significantly increase highly active Mn4+, Co3+, and oxygen defects, while density functional calculation results suggest that metal-oxygen covalency of S-CoMn2O4 can enhance the shrinking energy difference of Co 3d-O 2p and Mn 3d-O 2p centers, which can explain the enhancement of OER/ORR activities. What's more, the S-CoMn2O4 based zinc-air battery displays excellent open voltage of 1.52 V, power density of 108.3 mW cm(-2), specific capacity of 808.2 mA h g(-1) at 10 mA cm(-2), and good cycling stability. This work shows that the doping of heteroatom in the spinel materials can provide a feasible pathway to obtain optimized bifunctional catalysis for power sources devices.

Automated summary

The strategy of introducing heteroatom sulfur in CoMn2O4 boosts bifunctional electrocatalysis, with the optimized S-CoMn2O4 sample displaying enhanced performance in OER and ORR. The presence of sulfur increases active metal-oxygen centers, leading to improved catalytic activities. Additionally, S-CoMn2O4-based zinc-air battery shows excellent electrochemical performance and cycling stability.