Strengthened dipole-dipole interaction on high-entropy oxide electrocatalysts for high-rate and excellently stable lithium-sulfur batteries

Abstract

Electrocatalysts are an effective strategy to mitigate the shuttling effect of lithium polysulfides (LiPSs) and accelerate the redox kinetics of LiPSs in lithium-sulfur (Li-S) batteries. However, traditional electrocatalysts only have a single active site and often undergo structural collapse and aggregation during charging and discharging, resulting in reduced catalytic performance. Herein, the two-dimensional (2D) polar high-entropy La_0.71Sr_0.29Co_0.21Ni_0.20Fe_0.19Cr_0.20Cu_0.20O₃ (LCO-HEO) nanosheets were rationally designed and successfully synthesized to address this issue. The distinct functional polar sites in LCO-HEOs were formed by the d-d orbital hybridization between spatially coupling adjacent transition metals, which can strengthen the dipole-dipole interaction between polar LCO-HEOs and polar LiPSs. 2D polar LCO-HEO nanosheets can efficiently capture and trigger the tandem catalysis of polar LiPSs during their sequential conversion. The S/LCO-HEO composite cathode exhibits a high specific capacity of 1161.1 mA h g⁻¹ at 1.0 C, with an ultralow capacity attenuation rate of 0.036% per cycle over 1200 cycles, and achieves stable cycling for 1500 cycles even at 8.0 C. Furthermore, even with a high sulfur loading (5.5 mg cm⁻²) and a low electrolyte/sulfur (E/S) ratio (4.0 µL mg⁻¹), the S/LCO-HEO composite cathode shows desirable sulfur utilization and good cycle stability. This work demonstrates the feasibility of high entropy-driven multiple distinct functional polar sites for high-rate and long-cycle Li-S batteries.