From 2D to 3D: WS2/MoS2 heterostructure in-situ anchored on Ti3C2Tx MXene with enhanced ion/electron migration and sodium storage at −20 ℃

Abstract

Layered transition metal dichalcogenides (TMDs), featuring robust electrochemical activity, high capacity, and large interlayer spacing, have attracted widespread interest in research on sodium storage. However, the limitations in dynamics and structure expansion lead to degraded cycling life and rate capability, especially in cold climate with low temperatures. Generally, heterostructure engineering, combined with conductive matrix, gives a promise towards enhancing electronic transportation, accelerating ionic diffusion, and alleviating large structure change of layered TMDs upon sodium storage. Herein, a robust WS2/MoS2 heterostructure, rendering ultrafast charge transfer, is presented, and further hybridization with layered conductive Ti3C2Tx MXene results in three-dimensional crosslinked nanoarchitectonics, leading to electrochemical performance at 25 °C and -20 °C, which shows only 0.03 % capacity degradation per cycle up to 2800 cycles at 2.0 A g−1 (25 °C). Strikingly, the desired WS2/MoS2/Ti3C2Tx exhibits a high capacity of 293.7 mAh g−1 (100 cycles) at 0.1 A g−1 even at −20 °C. Besides, density functional theory calculations further manifest the decreased sodium diffusion barrier and facilitated charge-transfer dynamics in the designed heterostructure with Ti3C2Tx. More importantly, this work not only represents the correlation between structure and performance for target electrode, but also provides a deep insight for the rational design of heterostructure/Ti3C2Tx MXene for next-generation high-performance electrode materials.