Regulating Fe Aggregation State via Unique FeNV Pre‐Coordination to Optimize the Adsorption‐Catalysis Effect in High‐Performance Lithium‐Sulfur Batteries

Abstract

AbstractLithium‐sulfur batteries (LSBs) suffer from uncontrollable shuttling behavior of lithium polysulfides (LiPSs: Li2Sx, 4 ≤ x ≤8) and the sluggish reaction kinetics of bidirectional liquid‐solid transformations, which are commonly coped through a comprehensive adsorption‐catalysis strategy. Herein, a unique FeNV pre‐coordination is introduced to regulate the content of “dissociative Fe3+” in liquid phase, realizing the successful construction of N‐doped micro‐mesoporous “urchin‐like” hollow carbon nanospheres decorated with single atom Fe‐N4 sites and VN nanoparticles (denoted as SA‐Fe/VN@NMC). The strong chemisorption ability toward LiPSs and catalyzed Li2S decomposition behavior on VN, along with the boosted reaction kinetics for sulfur reduction on SA‐Fe sites are experimentally and theoretically evidenced. Moreover, the nanoscale‐neighborhood distribution of VN and SA‐Fe active sites presents synergistic effect for the anchoring‐reduction‐decomposition process of sulfur species. Thus SA‐Fe/VN@NMC presents an optimized adsorption‐catalysis effect for the whole sulfur conversion. Therefore, the SA‐Fe/VN@NMC based Li‐S cells exhibit high cyclic stability (a low decay of 0.024% per cycle over 700 cycles at 1 C, sulfur content: 70 wt%) and considerable rate performance (683.2 mAh g−1 at 4 C). Besides, a high areal capacity of 5.06 mAh cm−2 is retained after 100 cycles under the high sulfur loading of 5.6 mg cm−2. This work provides a new perspective to design the integrated electrocatalysts comprising hetero‐formed bimetals in LSBs.