Boosting Solid-Solid Conversion Kinetics via Electron-Pinned Interface Engineering for High-Energy-Density Li-S Batteries.

Abstract

The pursuit of high-energy-density lithium-sulfur (Li-S) batteries necessitates the use of lean electrolyte conditions. However, this goal is severely hampered by the sluggish kinetics of the sulfur reduction reaction (SRR), especially in the "solid-solid" conversion stage, where each step requires distinct active sites with specific electron-donating capabilities. Herein, we report a catalyst architecture that integrates "long-range order" with "local disorder", creating gradient-ordered active sites through amorphous nanodomain modification and precise local electronic structure regulation. This catalyst, termed an electron-pinned interface catalyst (EPIC) and denoted as a-FeOOH@Fe/AlO_x, exhibits synergistic catalytic enhancement via multi-level electronic interactions. Operando studies and DFT simulations reveal that the catalyst establishes conductive pathways facilitated by its gradient electron-donating properties, thereby decoupling the SRR process and significantly enhancing the "solid-solid" conversion efficiency. Under lean electrolyte conditions, this catalyst achieves a high areal capacity of 10.7 mAh·cm^-2 at a sulfur loading of 10.2 mg·cm^-2, exhibits 94.2% capacity retention after 150 cycles in a pouch cell, and enables stable operation of a 3.6 Ah pouch cell with an energy density of 418.6 Wh·kg^-1. This strategy effectively overcomes the reaction kinetic limitations in lean electrolyte conditions, providing valuable insights and a novel design paradigm for future high-energy-density Li-S batteries.