Establishing Transition Metal Phosphides as Effective Sulfur Hosts in Lithium–Sulfur Batteries through the Triple Effect of “Confinement–Adsorption–Catalysis”

Abstract

AbstractStructurally optimized transition metal phosphides are identified as a promising avenue for the commercialization of lithium–sulfur (Li–S) batteries. In this study, a CoP nanoparticle‐doped hollow ordered mesoporous carbon sphere (CoP‐OMCS) is developed as a S host with a “Confinement–Adsorption–Catalysis” triple effect for Li–S batteries. The Li‐S batteries with CoP‐OMCS/S cathode demonstrate excellent performance, delivering a discharge capacity of 1148 mAh g−1 at 0.5 C and good cycling stability with a low long‐cycle capacity decay rate of 0.059% per cycle. Even at a high current density of 2 C after 200 cycles, a high specific discharge capacity of 524 mAh g−1 is maintained. Moreover, a reversible areal capacity of 6.56 mAh cm−2 is achieved after 100 cycles at 0.2 C, despite a high S loading of 6.8 mg cm−2. Density functional theory (DFT) calculations show that CoP exhibits enhanced adsorption capacity for sulfur‐containing substances. Additionally, the optimized electronic structure of CoP significantly reduces the energy barrier during the conversion of Li2S4 (L) to Li2S2 (S). In summary, this work provides a promising approach to optimize transition metal phosphide materials structurally and design cathodes for Li–S batteries.