Uniform coverage of high-loading sulfur on cross-linked carbon nanofibers for high reaction kinetics in Li–S batteries with low electrolyte/sulfur ratio

Abstract

The aggregation of high-loading sulfur on host materials at low carbon/sulfur (C/S) ratio results in limited S ↔ Li₂S reaction kinetics and the shuttle effect of polysulfide, which is a bottleneck for the development of lithium–sulfur (Li–S) batteries with high energy densities. Herein, we demonstrate that uniform coverage of high loading amount of sulfur on a cross-linked carbon nanofiber network (TiC@CNF) can be achieved in Li–S batteries, which was realized by the denseness and well distribution of pores in the three-dimensional weave of TiC@CNF. It significantly increases the reaction kinetics and inhibits the shuttle effect under lean electrolyte conditions. Impressively, at a sulfur loading of as high as 12.5 mg cm⁻² (S/C ratio, 4.56), the areal capacity of Li–S batteries with TiC@CNF can maintain over 9 mA h cm⁻² for 150 cycles at an electrolyte/sulfur ratio of 6 μL mg⁻¹. The cathode structure design for high-loading sulfur provides a powerful strategy to realize fast S ↔ Li₂S reaction kinetics in the high energy density Li–S batteries.