Ultrafine Ti3C2 MXene Nanodots-Interspersed Nanosheet for High-Energy-Density Lithium–Sulfur Batteries

Abstract

Nanostructured carbon materials have been extensively used for encapsulating sulfur and improving cyclic stability of lithium–sulfur (Li–S) batteries, but high carbon content and low packing density greatly limit their volumetric energy density. Herein, we present MXene-based Ti 3 C 2 T x (T x stands for the surface terminations) nanodots-interspersed Ti 3 C 2 T x nanosheet (TCD-TCS) to accomplish spatial immobilization and conversion of high-loaded sulfur species. Rich surface polar sites in TCD-TCS enhance structural integrity of the resultant electrode, while the absence of the carbon-based materials and conductive additives results in high tap density of the cathode materials. The TCD-TCS/S electrode exhibits an almost theoretical discharge capacity at a medium sulfur loading of 1.8 mg cm –2 . Notably, ultrahigh volumetric capacity (1957 mAh cm –3 ) and high areal capacity (13.7 mAh cm –2 ) are synchronously achieved at a high sulfur loading of 13.8 mg cm –2 . The mechanism study of sulfur evolution during discharge process highlights the importance of the integration of MXene-based nanodots and nanosheets in Li–S batteries. This proposed methodology holds great promise for the development of various high-performance energy storage materials.