Oxygen deficient Eu₂O_3−δ synchronizes the shielding and catalytic conversion of polysulfides toward high-performance lithium sulfur batteries

Lithium-sulfur batteries (LSBs) are promising energy storage systems due to their low cost and high energy density. However, sluggish reaction kinetics and the “shuttle effect” of lithium polysulfides (LiPSs) from sulfur cathode hinder the practical application of LSBs. In this work, a separator loaded with the Eu₂O_3−δ nanoparticles/carbon nanotube interlayer is designed to immobilize LiPSs and catalyze their conversion reaction. The oxygen-deficient Eu₂O_3−δ nanoparticles, with abundant catalytic sites, promote LiPSs conversion kinetics even at high current densities. Moreover, the unique 4f electronic structure of Eu₂O_3−δ effectively mitigates undesired sulfur cathode crossover, significantly enhancing the cycling performance of LSBs. Specifically, a high capacity of 620.7 mAh/g at a rate of 5 C is achieved, maintaining at 545 mAh/g after 300 cycles at 1 C. This work demonstrates the potential application of rare earth catalysts in LSBs, offering new research avenues for promoting dynamic conversion design in electrocatalysts.