Collaborative design of Li–S batteries using 3D N-doped graphene aerogel as a sulfur host and graphitic carbon nitride paper as an interlayer

Abstract

Lithium–sulfur batteries (LSBs) have been widely investigated due to their high energy densities; however, their practical applications have still been limited by their poor cycling stability owing to the shuttle mechanism effect, volume expansion, soluble polysulfides, and the poor electrical conductivity of sulfur and Li₂S. To address these issues, sulfur was loaded into a conductive 3D nitrogen-doped reduced graphene oxide aerogel (NG_ae) host with a finely tuned nitrogen doping content. In addition, an interlayer of graphitic carbon nitride coated on flexible and conductive carbon fiber paper (g-C₃N₄/CFP) was inserted between the cathode and the polymer separator to trap the soluble polysulfides. It was found that the as-fabricated LSB using the NG_ae host with 4.2% N doping content and the g-C₃N₄/CFP interlayer can provide a specific capacity of 1271 mA h g⁻¹ at 0.1C with excellent stability over 400 cycles. The capacity fading is rather small (only 0.068% per cycle) while the coulombic efficiency is rather high (ca. 100%). This battery may be practically used in high-energy applications.