硫黄電極触媒の電子状態を二重欠陥で調整し、先進リチウム硫黄電池の酸化還元速度を加速する

The lithium polysulfides (LiPSs) shuttle effect and sluggish sulfur redox kinetics hinder the cycling stability and sulfur utilization of lithium‑sulfur (Li-S) batteries. Herein, a dual-defect engineering strategy is proposed to tailor the electronic state of sulfur electrocatalysts. This is exemplified by synthesizing a dual-defect electrocatalyst of oxygen-deficient manganese-doped Fe₃O₄ and carbon nanotubes (Mn_dFe₃O_4-x@CNTs) via a one-step hydrothermal route. Theoretical analyses reveal the dual defects synergistically optimize the electronic structure of Fe₃O₄ by modulating its spin state. This leads to an upshift of the d-band center, strengthening the d-p orbital hybridization with LiPSs and significantly accelerating the bidirectional conversion kinetics. The interconnected mesoporous framework acts as a multifunctional host, offering ample space for sulfur loading and working synergistically with the catalytic centers to concentrate LiPSs for efficient conversion. Consequently, the composite cathode exhibits excellent performance, including a low capacity fading rate of 0.07 % per cycle over 500 cycles at 1C, a high-rate capacity of 892.1 mAh g^-1 at 3C, and an initial capacity of 582.7 mAh g^-1 at 0.2C under a high sulfur loading of 9.1 mg cm^-2. This work establishes a paradigm for developing high-performance Li-S batteries through precise defect engineering of mesoporous transition metal oxides.