Mastering Surface Sulfidation of MnP-MnO Heterostructure to Facilitate Efficient Polysulfide Conversion in Li─S Batteries.

The development of lithium-sulfur (Li─S) batteries has been hampered by the shuttling effect of lithium polysulfides (LiPSs). An effective method to address this issue is to use an electrocatalyst to accelerate the catalytic conversion of LiPSs. In this study, heterogeneous MnP-MnO nanoparticles are uniformly synthesized and embedded in porous carbon (MnP-MnO/C) as core catalysts to improve the reaction kinetics of LiPSs. In situ characterization and density functional theory (DFT) calculations confirm that the MnP-MnO heterostructure undergo surface sulfidation during the charge/discharge process, forming the MnS phase. Surface sulfidation of the MnP-MnO heterostructure catalyst significantly accelerated the SRR and LiS activation, effectively inhibiting the LiPSs shuttling effect. Consequently, the MnP-MnO/C@S cathode achieves outstanding rate performance (10 C, 500 mAh g) and ultrahigh cycling stability (0.017% decay rate per cycle for 2000 cycles at 5 C). A pouch cell with MnP-MnO/C@S cathode delivers a high energy density of 429 Wh kg. This study may provide a new approach to investigating the surface sulfidation of electrocatalysts, which is valuable for advancing high-energy-density Li-S batteries.