NbP-NbO Heterostructures with Engineered Built-In Electric Fields for Accelerated Lithium Polysulfide Conversion

To effectively regulate lithium polysulfides (LiPSs) and enhance their conversion kinetics, we designed a novel NbP-NbO heterostructure catalyst. Density functional theory calculations demonstrate that the NbP-NbO heterostructure generates a built-in electric field, which induces significant interfacial electron flow. This electron redistribution effectively lowers the reaction energy barrier for LiPS reduction and accelerates their conversion kinetics. Galvanostatic intermittent titration and in situ electrochemical impedance spectroscopy further elucidate the roles of activation energy and concentration gradients in LiPS conversion, while highlighting the influence of kinetic barriers and transport limitations on sulfur utilization efficiency. The NbP-NbO/C@S cathode delivers exceptional electrochemical performance, achieving a high specific capacity of 1463.6 mAh g^-1 at 0.2 C, outstanding cycling stability, and superior rate capability (704.9 mAh g^-1 at 5 C). Notably, a practical pouch cell incorporating this cathode exhibits a high energy density of 403 Wh kg^-1, underscoring its potential for real-world Li-S battery applications.