Synergistic Dual‐Gradient Architecture and Vacancy‐Engineered Catalytic Interfaces via p‐Band Modulation for High‐Reversibility Lithium–Sulfur Batteries

Abstract Lithium–sulfur (Li─S) batteries with high theoretical capacity have been regarded as one of the most promising energy storage systems. However, the shuttling and slow redox kinetics of lithium polysulfides (LiPSs) have seriously hindered their practical applications. Herein, a novel dual‐gradient design strategy is proposed based on 1D oxygenated vacancies containing SnO 2 decorated CNTs (SnO 2‐ x ‐CNTs) layer and a 2D MXene layer to functionalize the separator to precisely control the reaction interface of LiPSs. The generation of vacancies of SnO 2 causes the p‐band center of Sn to move toward the Fermi level, realizing the association process of adsorption‐capture‐conversion of LiPSs. Experimental findings reveal that the higher the vacancy concentration, the stronger the catalytic activity, but excessive vacancy concentration affects the crystal structure, thereby reducing cycling stability. The MXene underlayer acts as a nanobarrier, physically blocking and chemically anchoring LiPSs leaking from the upper SnO 2‐ x ‐CNTs layer. In addition, high capacity and stable circulation can be maintained even under high S load conditions. This design provides deeper insights into the synergistic effects between components of 1D catalysts and 2D materials in modified separator systems for the battery system suffering from the shuttle effect.