Solid-Liquid Synergy Enables a Trisulfur-Radical-Rich Microenvironment for Accelerated Li-S Conversion Kinetics.

Abstract

Understanding and regulating the rate-determining steps (RDSs) of lithium-sulfur batteries (LSBs) is crucial for enhancing their electrochemical performance. Herein, we propose a synergistic strategy that integrates a template sulfur host containing oxygen vacancies with a high-donor-number (high-DN) solvent as an additive of the traditional ether-based electrolyte. The strategy establishes a localized high-DN microenvironment with a significant concentration of trisulfur radicals on the cathode side. Both experiments and calculations confirm that trisulfur radicals serve as key mediators in accelerating the RDS from the intrinsically sluggish quasi-liquid-solid reaction to the more kinetically favorable trisulfur radicals-mediated conversion. Benefiting from the RDS enhancement mediated by trisulfur radicals, the LSB maintains an 85.4% capacity after 500 cycles at 1 C, with an average decay rate of only 0.03% per cycle. In addition, an initial capacity of 659.6 mAh g^-1 is achieved at 5 C or 1126.9 mAh g^-1 at a high sulfur loading of 4.6 mg cm^-2. This work presents a novel trisulfur radicals mediated-catalytic mechanism and breaks the limitations of the intrinsic RDS through integration of interface engineering and electrolyte modulation.