Monodisperse High-Entropy Metal Oxide Nanoparticles Encapsulated Within 2D Porous Carbon Sheets for Enhanced Catalytic Activity in Lithium–Sulfur Batteries

Abstract

High-entropy oxides have garnered significant attention as a promising catalyst for lithium–sulfur batteries. However, their development has been hindered by intractable structures and unclear catalytic mechanisms. We conducted simultaneous structural engineering of high-entropy metal oxides nanoparticles embedded in 2D porous carbon sheets (HEO-C) across atomic, nano, and micro scales. In the prepared HEO nanoparticles, we observed and confirmed the presence of numerous ion vacancies, likely resulting from lattice distortions. The presence of these ionic vacancies can furnish supplementary edge adsorption and catalytic sites for lithium polysulfide conversion, and augment catalytic activity through modulation of the d-band center. Furthermore, the high entropy of HEO-C attributes in inducing the rapid dissociation and conversion of long-chain lithium polysulfides, improving redox kinetics. As a result, cells equipped with the HEO-C catalyst exhibited outstanding electrochemical rate performance, delivering 761 mAh g−1 at 3 C, along with excellent cycling stability—retaining 80.44% capacity after 1000 cycles at 1 C. The high surface area of HEO-C facilitates the reduction of inactive components in the cell while preserving the catalytic activity, enhancing the potential for practical application. The assembled pouch cell with the HEO-C catalyst achieved a reversible capacity of 968 mAh g−1 and retained 81.33% of its capacity after 200 cycles at 0.1 C.