Spatial reinforced cascade catalysts towards optimization of Polysulfide conversion kinetics in Lithium Sulfur batteries

Abstract

The energy conversion and utilization of lithium sulfur batteries are inextricably linked to the adsorption-catalysis-conversion processes of polysulfide intermediates at the cathode side. Herein, we report novel carbon nanofibers (CNFs) bridged spatial reinforced multifunctional catalysts (Ni-CNFs-MnS) to accelerate the cascade adsorption-catalysis-conversion processes of carbon/sulfur cathodes prepared via vesicle reactors. The composite catalysts grow quasi-vertically on the carbon hosts, with CNFs acting as the bridges to connect top-end Ni nanoparticles (NPs) and bottom-end MnS NPs to achieve synergistic cascade desolvation-adsorption-catalysis-conversion for lithium polysulfides. In situ Raman and theoretical calculation results reveal that the top-end Ni NPs can effectively enhance the desolvation/adsorption and catalytic conversion of long-chain polysulfides, while the bottom-end MnS NPs could preferentially adsorb and catalytically convert short-chain polysulfides. Meanwhile, CNFs serve as conductive bridges to offer rapid electron/ion transfer paths for polysulfide conversion, and simultaneously provide spatial confinement to suppress the shuttle effect of polysulfides. Accordingly, our cascade configuration combines multifunctional catalytic sites and carbon bridges with different spatial dimension to obtain fast adsorption-catalysis-conversion processes for polysulfides, endowing the carbon/sulfur cathodes with enhanced high-rate capacity and superior cycling stability. This work provides valuable insights into the design of high-efficiency spatially bridged cascade catalysts for multistage conversion reactions of sulfur.