Revealing the mechanism of TM@P1N3 single-atom catalyst in sulfur redox reactions

Lithium-sulfur (Li-S) batteries are distinguished by their high theoretical capacity and relatively low theoretical cost. Overcoming the well-known shuttle effect is of paramount importance for the development of highperformance Li-S batteries. While various advanced cathode materials have significantly enhanced the reaction kinetics, the intricate mechanism of the sulfur reduction reaction (SRR) continues to present a challenge for the improvement of Li-S battery performance. Consequently, an extensive investigation into the electrocatalytic mechanism is undoubtedly one of the key aspects to direct the development and real-world use of cathode materials. In this paper, a single atom catalyst synthesized (SACs) with P1N3 coordinated transition metal (TM) elements is used as the cathode catalytic material, and an electrocatalytic model is established. The detrimental effects of the shuttle effect in Li-S batteries are mitigated, while the kinetic mechanism of the cathode reaction is enhanced, thereby improving the overall performance. The chemical mechanism of the rate-determining step in the SRR has been elucidated using a TM@P1N3 SACs. It is found that Sc@P1N3 with a lower overpotential and lower ICOHP value can accelerate the SRR. Effective descriptors such as overpotential and energy barrier can be employed as measures of the SACs. This work provides a robust theoretical foundation for the design of superior electrocatalysts for Li-S batteries.