High‐entropy stabilized oxides derived via a low‐temperature template route for high‐performance lithium‐sulfur batteries

Abstract

AbstractIt is a long‐standing issue that the sluggish polysulfide conversion and adverse shuttling effects impede the development of lithium‐sulfur (Li‐S) batteries with high energy density and cycling stability, which necessitate the exploration of new electrocatalysts to facilitate the practical applications of Li‐S batteries. Herein, a single‐phase high‐entropy stabilized oxide (Ni0.2Co0.2Cu0.2Mg0.2Zn0.2)O (HEO850) is successfully prepared through a novel low‐temperature annealing strategy from a self‐sacrificing metal–organic frameworks (MOFs) template and then integrated into the sulfur host, where it functions as both the catalytic converter and chemical inhibitor towards the shuttle species. Furthermore, the synergistic contribution of randomly dispersed metal elements and the exposure of affluent active sites enable the chemical encapsulation of soluble polysulfides and accelerate conversion kinetics. The HEO850/S/KB cathode (KB: ketjen black; sulfur content: 70 wt.%) delivers a substantially higher initial specific discharge capacity of ~1244 mAh g−1 in comparison to MEO/S/KB (MEO: medium entropy oxide; ~980 mAh g−1), LEO/S/KB (LEO: low entropy oxide; ~908 mAh g−1), and routine S/KB cathodes (~966 mAh g−1), which is well retained at ~784 mAh g−1 after 800 cycles at 0.5 C with a low capacity decay rate of ~0.043% per cycle. Moreover, when the HEO850/S/KB cathode is processed with a high areal sulfur loading (~4.4 mg cm−2), the resulting Li‐S battery also performs well, with a high initial specific capacity of ~1044 mAh g−1 at 0.1 C and 85% capacity retention after 100 cycles. This study highlights the potential application of HEOs in enhancing the performance of Li‐S batteries and provides a novel strategy in synthesizing the HEOs at a relatively low annealing temperature for various energy conversion and storage applications.image