Manipulating Orbital\nHybridization of CoSe<sub>2</sub> by S Doping for the Highly Active\nCatalytic Effect of Lithium–Sulfur\nBatteries

In recent years, various transition metal compounds have\nbeen extensively\nstudied to deal with the problems of slow reaction kinetics and the\nshuttle effect of lithium–sulfur (Li–S) batteries. Nevertheless,\ntheir catalytic performance still needs to be further improved by\nenhancing intrinsic catalytic activity and enriching active sites.\nDoping is an effective means to boost the catalytic performance through\nadjusting the electron structure of the catalysts. Herein, the electron\nstructure of CoSe<sub>2</sub> is adjusted by doping P, S with different\np electron numbers and electronegativity. After S doping (S–CoSe<sub>2</sub>), the content of Co<sup>2+</sup> increases, and charge is\nredistributed. Furthermore, more electrons are transferred between\nLi<sub>2</sub>S<sub>4</sub>/Li<sub>2</sub>S and S–CoSe<sub>2</sub>, and optimal Co–S bonds are formed between them with\noptimized d–p orbital hybridization, making the bonds of Li<sub>2</sub>S<sub>4</sub>/Li<sub>2</sub>S the longest and easy to break\nand decompose. Consequently, the Li–S batteries with the S–CoSe<sub>2</sub>-modified separator achieve improved rate performance and\ncycling performance, benefiting from the better bidirectional catalytic\nactivity. This work will provide reference for the selection of the\nanion doping element to enhance the catalytic effect of transition\nmetal compounds.