Circuit board-like CoS/MXene composite with superior performance for sodium storage

Abstract

Electrochemical performance of Ti3C2 MXene sheet is restricted by the modest specific capacity and self-restacking. To conquer the defects, we designed cobalt sulfide and Ti3C2 MXene flake composite (CoS/MXene) with heterolayered architecture, in which ultrafine CoS nanoparticles (∼6 nm) were anchored on MXene flakes. In this structure, the role of MXene is similar to printed circuit board, which providing conductive network. As anode for sodium ion batteries, CoS/MXene electrode delivers a high reversible capacity of 267 mA h g−1 after 1700 cycles at 2 A g−1 with an extreme low capacity decay rate of only ∼0.0072% per cycle, and an outstanding rate performance with 272 mA h g−1 at 5 A g−1.