Facile “Lotus Blooming” Strategy to Synthesize a 3D Carbon Nanosheet/Carbon Nanotube Framework with Embedded Co Nanocrystals for High-Performance Lithium–Sulfur Batteries

Abstract

Lithium−sulfur batteries (LSBs) are expected to be one of the most promising next-generation energy storage systems due to their high energy density and theoretical specific capacity. However, the poor electrical conductivity, significant volume expansion during discharging, and "shuttle effect" of lithium polysulfides (LiPSs) have seriously impeded the further development of LSBs. Herein, inspired by the "lotus blooming" procedure, a 3D composite host material made up of cobalt nanocrystals/carbon nanosheets/carbon nanotubes (Co/CNS/CNT) is synthesized by in situ growth of CNTs to exfoliate off ultrathin CNSs from 0D precursors in a one-step method. As expected, the 3D structure of Co/CNS/CNT provides horizontal and vertical transmission channels for electrons/ions and is conducive to the uniform loading of sulfur and infiltration of the electrolyte. Furthermore, the Co/CNS/CNT host material realizes the synergistic effect of physical and chemical adsorption/catalysis through its 3D structure and fine Co nanocrystals. The Co/CNS/CNT-S cathode shows excellent cycle performance (after 500 cycles at a current density of 1C, the remaining capacity is 660.6 mAh g −1 , and the capacity decay rate per cycle is only 0.06%). This work achieves the transformation of 0D precursors into a 3D framework through a facile strategy, which has great application potential in LSBs.