Oxygen vacancy enabled fabrication of dual-atom Mn/Co catalysts for high-performance lithium–sulfur batteries

Abstract

To tackle the parasitic polysulfide shuttle effect of lithium sulfur batteries, we herein report a highly active Mn/Co–N–C catalyst with dual atom Mn/Co active sites coordinated on a N doped carbon support. Fabrication of Mn/Co–N–C is enabled by using cobalt doped, oxygen vacancy enriched MnO₂ (Co–MnO₂|O_v) as an initiator for aniline polymerization. The Co–MnO₂|O_v initiator can release Co/Mn ions during the polymerization reaction and be used as a metal ion source for the catalyst; the oxygen vacancies can create abundant defects in the carbon structure resulting from pyrolysis of the synthesized polyaniline, which is conducive to increasing Mn/Co loading. The Li–S battery equipped with a Mn/Co–N–C modified separator exhibits an initial discharge capacity of 1662 mA h g⁻¹ at 0.1C and 625 mA h g⁻¹ at 6C. The capacity of 816 mA h g⁻¹ achieved at 2C decays only 0.036% per cycle after 1000 cycles. At a high sulfur loading of 14.1 mg cm⁻², the battery yields capacities of 798.6 mA h g⁻¹ and 7.566 mA h cm⁻² at 0.1C, which are retained by 63.9% and 64.7%, respectively, after 110 cycles. DFT calculations reveal that the Mn/Co–N–C catalyst enhances the adsorption capacity and favors electron transfer. This work provides an effective, novel strategy to prepare a highly active Mn/Co–N–C dual-atom catalyst, which shows a good prospect for application in energy storage devices.