Accelerated Sulfur Evolution Reactions by TiS2/TiO2@MXene Host for High-Volumetric-Energy-Density Lithium-Sulfur Batteries

Abstract

The poor cycling stability and low volumetric energy density of lithium-sulfur batteries compared with lithium-ion batteries are hindering their practical applications. Here, it is demonstrated that a dense sulfur electrode containing heavy TiS2/TiO2@MXene heterostructures can tackle these issues. It is observed that the TiO2 part functionally anchors the lithium polysulfides through the strong chemical affinity, and the TiS2 part serves as an efficient electrocatalyst to enhance the kinetics of sulfur evolution reactions. Benefitting from these synergistic effects, the TiS2/TiO2@MXene heterostructures effectively suppress the shuttle effects, leading to superior cyclability of the sulfur cathode with a low capacity decay of 0.038% per cycle for 500 cycles at a current rate of 1 C. More encouragingly, a highly dense S/TiS2/TiO2@MXene cathode exhibits a high volumetric energy density of 2476 Wh L-1 (based on the volume of the composite) at a high sulfur mass loading of 7.5 mg cm(-2) and lean electrolyte of 5 mu L mg(-1). The electrochemical performance is comparable to or even superior to the lithium-ion and lithium-sulfur batteries reported in the literature. This study provides an effective strategy to design stable and high-volumetric-energy-density lithium-sulfur batteries for practical energy storage applications.