Unlocking Activity Origins of High‐Entropy Spinel Oxides: Tailoring Octahedral Coordination Chemistry for Accelerated Polysulfide Conversion

Abstract High‐entropy transition metal oxides with a spinel structure exhibit excellent catalytic activity for the redox reactions of sulfur species in lithium‐sulfur batteries (LSBs). However, the underlying origin of their catalytic activity—driven by geometric configuration and electronic structural evolution—remains unclear. Herein, it is applied X‐ray absorption fine structure (XAFS) spectroscopy, complemented by ex situ X‐ray photoelectron spectroscopy analysis and theoretical calculations, to establish the structure‐activity correlation of the catalyst. Using spinel‐structured Co 3 O 4 as a model catalyst, two systems are constructed as LSB catalysts, specifically a medium‐entropy oxide, (FeCoNi) 3 O 4 , and a high‐entropy oxide (HEO), (FeCoNiMnZn) 3 O 4 , by incorporating different metal elements to modulate the ratio between Co‐occupied octahedral (Co Oct ) and tetrahedral (Co Tet ) sites. XAFS experiments and theoretical analyses reveal the geometric configuration and electronic structural evolution of HEO catalysts. Meanwhile, the octahedral site is recognized as the primary active center. Additionally, the weakened covalency (strengthened polarity) of the Co Oct –O bonds in the HEOs serves as the origin of the enhanced redox kinetics of reversible polysulfide conversion, which is supported by theoretical calculations. This work provides new insights into the catalytic mechanism of the spinel‐structured high‐entropy transition metal oxide electrocatalysts, thereby facilitating the rational design of highly efficient electrocatalysts for advanced LSBs.