Multifunctional Three-Dimensional Bicontinuous Heterofibrous Scaffold for Kinetically Accelerated Polysulfide Trapping and Conversion in Lithium–Sulfur Batteries

Abstract

Further development of lithium–sulfur (Li–S) batteries is restricted by the insulation of sulfur and the shuttle effect of lithium polysulfide (LiPSs). Herein, we propose a multifunctional freestanding three-dimensional (3D) bicontinuous heterofibrous carbon nanotube–carbon nanofiber (CNTs-CNFs) scaffold via the chemical vapor deposition (CVD) strategy as a polysulfide-engulfing system and a conductive network in the cathode. CNFs construct a continuous network that serves as a freestanding substrate with moderate conductivity for CNTs to grow. The as-grown CNTs with cross-twisted root and cross-winding tips reduce the interfacial impedance of sulfur, achieving up to 77.88% loading. They also act as inserted networks with excellent electrical conductivity in active substance, which facilitate the diffusion and transport of electrons and ions and accelerate redox kinetics, with the initial discharge capacity of 1412.5 mAh g–1 at a current density of 0.2 C. Moreover, the cross-winding of CNT tips in different spatial orientations plays a great role as well in immobilizing the shuttle of soluble LiPSs via the synergistic effect of physical blocking and chemical adsorption. Eventually, the cycle performance is significantly improved with the maintained capacity of 607.7 mAh g–1 after 500 cycles at a current density of 1 C.

Three-Dimensional Carbon Networks Decorated with Co Nanocatalysts as Multifunctional Interlayers for a High-Performance Lithium–Sulfur Battery

“…Herein, a three-dimensional structured dense carbon network design decorated with highly active nanocatalyst is developed to serve as a multifunctional interlayer. In this design, rGO is infiltrated into the internal skeleton of the CF film, forming a dense rGO-CF substrate on which in-situ catalytic growth of carbon nanotubes (CNTs) is introduced by the chemical vapor deposition (CVD) method. , The rGO is synthesized by vacuum filtration followed by high-temperature treatment under Ar atmosphere, allowing the rGO to penetrate into the interstices of CF. The rGO and CF are tightly connected, forming a “bridge” for electron transportation.…”