Intercalation‐Conversion Hybrid Cathode Enabled by MXene‐Driven TiO₂/TiS₂ Heterostructure for High‐Energy‐Density Li–S Battery

Abstract

A dense electrode with high sulfur loading is a straightforward approach to increasing the energy density of lithium–sulfur battery (LSB), but the development of dense electrodes suffers from both fabrication challenges and electron/ion transport limitations. In addition, the shuttle effect of soluble lithium polysulfides and sluggish reaction kinetics cause declined utilization efficiency of the active material and poor cycling stability. Herein, a dense intercalation‐conversion hybrid cathode is prepared using MXene‐driven TiS 2 nano‐needles decorated with TiO 2 nanoparticles. The TiO 2 /TiS 2 heterostructure simultaneously possessing a high adsorption capability (TiO 2 ) and bidirectional electrocatalytic effect (TiS 2 ) is observed to effectively suppress lithium polysulfide shuttling and facilitate the sulfur conversion reactions. Furthermore, it is believed that TiS 2 provides additional capacity from the intercalation reaction and functions as a multichannel network to feed both Li + / e − to the active sulfur material due to its high electronic and ionic conductivities. Thanks to these synergistic effects, the LSB assembled using the TiO 2 /TiS 2 heterostructure exhibits high gravimetric and volumetric energy densities of 331 Wh kg −1 and 730 Wh L −1 , respectively, as well as superior cyclability at a high sulfur mass loading of 7.5 mg cm −2 and lean electrolyte of 2.5 μL mg −1 .