Porous sulfurized poly(acrylonitrile) nanofiber as a long-life and high-capacity cathode for lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have attracted great interest for next-generation batteries owing to their high capacity density and low cost. However, the drawbacks of the low conductivity of sulfur, serious “shuttle effect” and huge volume expansion during the charging/discharging cycles greatly limit their practical applications. In this work, we report the synthesis of porous sulfurized poly(acrylonitrile) (PAN/S) nanofibers via thermal treatment of PAN/poly(methyl methacrylate) (PMMA) nanofibers with elemental sulfur, resulting in 48 wt% of covalently bound sulfur formed in the composite. The unique porous structure of nanofibers enables enhanced diffusion dynamics of ions and electrons, thus improving the reactivity and conductivity of sulfur. As a consequence, the porous PAN/S cathode delivers a high reversible capacity of 1144 mA h g−1 after 100 cycles at a current rate of 0.2 C and a high rate performance with a reversible discharge capacity of 794 mA h g−1 at 2 C after 500 cycles.