Modulating the d-p orbital coupling of manganese chalcogenides for efficient polysulfides conversion in lithium–sulfur batteries

The commercialization of lithium-sulfur battery (LSB) is seriously limited by the shuttling effect and sluggish reaction kinetics. Metal chalcogenides have been widely used as catalysts to enhance electrochemical performance, but the modulation essence of these non-metal anions is unclear. Herein, cubic manganese chalcogenides (MnO, MnS, MnSe) with fixed cation (Mn) and various anions (O, S, Se) are synthesized, and the anion effect on the performance of LSBs is systematically investigated. Based on the complementary experimental characterization and advanced theoretical calculations, it is clear that the interfacial redox reaction dynamics are governed by the catalytic activity of manganese chalcogenides, while the catalytic activity is modulated by the gap between the d-band of cation and p-band of anion (Δd-p). Among these manganese chalcogenides, Se has the largest atom radius and lowest electronegativity, which makes the p-band center of Se move to the Fermi level, thus increasing the electron's energy to react. Consequently, the LSBs based on MnSe catalyst exhibit the best rate (613.5 mAh g−1 at 4C) and cyclic performance (847.5 mAh g−1 after 250 cycles at 0.2C). This comparative study may encourage more effort and provide a new paradigm for developing highly effective catalysts for high-performance LSBs.