Excimer ultraviolet-irradiated carbon nanofibers with ZnO interlayer for strong binding to lithium polysulfides

Abstract

Lithium–sulfur (Li–S) batteries have attracted significant attention due to their high theoretical specific capacity (1675 mAh g−1) and energy density (2600 Wh kg−1) as well as abundant natural reserves. However, polysulfide shuttling, low conductivity of sulfur species and low cell energy densities hinder the practical applications of these batteries. Herein, carbon nanofiber (CNF) is subjected to excimer ultraviolet (EUV) irradiation in ZnCl2 solution affording ZnO grains attached to the CNF (denoted as EUV-ZnO/CNF) as an interlayer for Li–S batteries. EUV-ZnO/CNF shows strong chemical anchoring and physical block effects on the polysulfides as CNF provide a conductive network allowing the fast transmission of electrons, and ZnO particles provide active sites to adsorb the polysulfide intermediate. The electrode with the EUV-ZnO/CNF interlayer exhibits a high initial discharge capacity of 1388.3 mAh g−1, and a capacity of 780.4 mAh g−1 is retained after 200 cycles with S loading of 1.55 mg cm−2. Our work demonstrates an effective and environmentally friendly method to prepare EUV-ZnO/CNF as an interlayer for high performance Li–S batteries.