Ultrathin Amorphous Iron Oxide Nanosheets for Improving the Electrochemical Performance of Li-S Batteries

The sluggish kinetics and diffusion of lithium polysulfide (LiPS) intermediates lead to the decline in the capacity and rate of high-energy lithium-sulfur (Li-S) batteries. Integrating adsorbents and electrocatalysts into the Li-S system is an effective strategy for suppressing the polysulfide shuttle and enhancing the redox kinetics of sulfur species. The disordered structure of the electrocatalysts exhibits significantly enhanced catalytic activity. By inducing more oxygen vacancies, this structure can not only effectively promote the adsorption behavior of LiPSs but also significantly enhance the intrinsic catalytic activity of the Li₂S product nucleation. Herein, an amorphous iron oxide-graphene oxide (FeO_x-GO) ultrathin nanosheet was developed for the adsorption and catalysis of LiPSs. Experiments showed that the FeO_x-GO-based cell exhibited excellent rate performance: a reversible capacity of 880 mAh g^-1 at 2C, along with ultralow capacity decay (a decay rate of only 0.08% per cycle). More notably, it demonstrated a stable performance under high sulfur loading conditions, achieving a high areal capacity of 5.5 mAh cm^-2. The synergistic effect at the FeO_x-GO interface optimized the electronic structure of active sites and adsorption energy barriers, facilitating the efficient acceleration of rapid redox reactions.