Catalytic Nano-Reactor Engineering of Metal Single-Atom Site and Metal-Free Chemical Group for Accelerating Sulfur Redox Electrocatalysis.

Precisely constructing atomic engineering of catalytic site and thus accelerating sulfur redox kinetics are meaningful but challenging for energy storage and conversion. Herein, the catalytic nano-reactor engineering containing Fe-N4 catalytic site and the adjacent PO chemical group as synergistic catalytic site (Fe-N4/CNPO) was first designed for Li-S batteries with remarkably improved performance. The adjacent PO chemical group of Fe-N4 site in catalytic nano-reactor simultaneously strengthened the adsorption of lithium polysulfides and facilitated the fracture of Li─S bonds by Li─O interaction, thus lowering the free energy change of potential-determining step and accelerating sulfur redox kinetics, which was further verified via density functional theory calculation. The optimized Fe-N4/CNPO modified separator exhibited much higher battery capacity of 1322.1 mAh g-1 at 0.2 C and enhanced long-term stability (low capacity decay of 0.08% per cycle over 500 cycles at 1.0 C). This work demonstrated the enormous potentiality of catalytic nano-reactor engineering containing metal single-atom catalytic site and chemical group as synergistic catalytic site for accelerating sulfur redox in metal-sulfur batteries.