Defectizing high‐entropy oxide with the introduction of Se to facilitate the kinetics for highly cycle‐stable lithium–sulfur batteries

Abstract As a novel material, high‐entropy compounds have attracted extensive attention in the field of lithium–sulfur battery host materials due to their diverse elemental composition with a wide range of properties. The ability to effectively mitigate the shuttle effect of lithium polysulfides and catalyze the bidirectional conversion of Li 2 S 2 /Li 2 S is crucial to enhance the overall performance of the battery. In this study, a unique sulfur host nanosized high‐entropy material comprising selenium‐doped HEO (AlCrFeCoNi) 3 O 4‐x ‐Se x is fabricated using an in situ thermal reduction and selenylation method. In the high‐entropy compounds, the introduction of Se causes that the generation of oxygen vacancies during the lattice distortion serves as ion transfer pathway and the formation of M‐Se bonds provides a high adsorption capability for LiPSs. Moreover, the polymetallic cooperative high‐entropy nanoparticles also provide numerous active sites favoring redox kinetics of the sulfur electrode. The resulting selenium‐doped HEO (AlCrFeCoNi) 3 O 4‐ x ‐Se x not only enhances discharge capacity but also maintains excellent capacity cycling stability. As a result, the HEO‐Se/S composite exhibits a specific capacity of 1233.9 mAh g −1 at 0.1C and experiences minimal capacity fading at a rate of 0.038% per cycle over 500 cycles at 0.2C, while host materials with sulfur loading of 4.33 mg cm −2 and E/S ratio of 5.88 μL mg −1 exhibit excellent capacity retention after 100 cycles at 0.2C. This work offers new insights into synthesizing high‐entropy nanomaterials for improving the electrochemical performance of Li–S batteries.