Hollow Ti3C2Tx MXene@CoSe2/N-doped carbon heterostructured composites for multiphase electrocatalysis process in lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have ultrahigh theoretical energy density (2600 Wh kg-1) and large specific capacity (1675 mAh g-1), making them an ideal battery supply for energy storage systems. However, the sluggish kinetics of the heterogeneous sulfur redox reaction, notorious shuttle effect, and volume expansion hindered further application. Herein, the MOF-derived CoSe2 nanoparticles were embeddeded on the N-doped carbonlayered MXene hollow spheres to obtain MXene@CoSe2/NC heterostructured composites. Density functional theory (DFT) calculations confirmed that: The MXene@CoSe2 heterojunction composite exhibited an enhanced affinity for polysulfides and reduced the energy barrier for Li2S decomposition. Consequently, the MXene@CoSe2/NC electrodes achieved excellent performance for a large areal capacity of 3.343 mAh cm-2 with a sulfur loading of 3.5 mg cm-2. The MXene@CoSe2/NC based Li-S pouch cell performed an excellent stability for 200 cycles at 1 C rate. In this study, we propose an effective method of MXene/transition-metal selenide electrocatalysts for multiphase electrochemical reactions.

Automated summary

In this study, MXene@CoSe2/NC heterostructured composites were synthesized by embedding CoSe2 nanoparticles onto the surface of N-doped carbon layered MXene hollow spheres. The composites exhibited enhanced electrochemical performance and excellent stability under large areal capacity.