Immobilizing VN ultrafine nanocrystals on N-doped carbon nanosheets enable multiple effects for high-rate lithium—sulfur batteries

Abstract

The exploitation of new sulfiphilic and catalytic materials is considered as the promising strategy to overcome severe shuttle effect and sluggish kinetics conversion of lithium polysulfides within lithium-sulfur batteries. Herein, we design and fabricate monodisperse VN ultrafine nanocrystals immobilized on nitrogen-doped carbon hybrid nanosheets (VN@NCSs) via an one-step in-situ self-template and self-reduction strategy, which simultaneously promotes the interaction with polysulfides and the kinetics of the sulfur conversion reactions demonstrated by experimental and theoretical results. By virtue of the multifunctional structural features of VN@NCSs, the cell with ultrathin VN@NCSs (only 5 µm thickness) modified separator indicates improved electrochemical performances with long cycling stability over 1,000 cycles at 2 C with only 0.041% capacity decay per cycle and excellent rate capability (787.6 mAh·g−1 at 10 C). Importantly, it delivers an areal reversible capacity of 3.71 mAh·cm−2 accompanied by robust cycling life.