Precisely optimizing polysulfides adsorption and conversion by local coordination engineering for high-performance Li-S batteries

Incorporating electrocatalysts into lithium-sulfur (Li-S) batteries is a promising strategy to relieve the deleterious shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPSs). However, atomic modulation of the electrocatalysts to boost the catalytic activity is still challenging because of their intrinsic structural complexity. Herein, we report the theoretical prediction and experimental realization of Mo single atoms with different ligand coordinations (Mo-NxC3−x), wherein we find that the LiPSs adsorption and conversion are well modulated by the atomic coordination species of single Mo centers. The resultant Mo-N2C1 displays a moderate bonding strength with LiPSs in comparison with the Mo-N1C2 and Mo-N3 counterparts, which facilitates the charge transfer kinetics and reduces the Li2S precipitation/decomposition energy barrier. Consequently, the constructed Li-S batteries with Mo-N2C1 present a durable cyclability with a low capacity decay rate of 0.055% each cycle over 1000 cycles at a high current rate of 10 C and a decent areal capacity of 4.27 mAh cm−2 after 100 cycles with a low electrolyte/sulfur ratio of 8 µL mg−1. This work demonstrates that optimizing LiPSs adsorption and conversion through local composition and coordination modulation is an effective strategy for developing efficient and durable electrocatalysts for advanced Li-S batteries.