Deciphering the Modulation Essence of p Bands in Co-Based Compounds on Li-S Chemistry

Despite the fact that metal-based compounds have been extensively used as sulfur cathode additives, large variations in electrochemical performance have been commonly observed from one material to another, which cannot be simply explained by the adsorption capability. Herein, we have systematically studied the kinetic behaviors of Li-S chemistry on Co-based compounds with fixed metal cation and varied non-metal anions, and deciphered the intrinsic modulation essence of the anions. Among the Co-based compounds, CoP exhibits the lowest overpotential for polysulfide transformation. Even at 40.0 C, S@CoP/rGO still delivers a high capacity of 417.3 mA hr g−1 and an unprecedented power density of 137.3 kW kg−1, representing the best rate performance. DFT analysis reveals that the performance variations mainly originate from the shift of p band centers, which modulate the interfacial electron transfer dynamics. This work could unlock the potential of band engineering for Li-S batteries and beyond.