Effect of sulfurized polyacrylonitrile-g-rGO composition on the specific capacity and cycling stability of lithium sulfur batteries

Abstract

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for the commercialization of lithium-sulfur batteries with extremely stable cycling performance. However, its inherent low sulfur content and poor electrical conductivity severely impairs its electrochemical performance. In this work, we construct a sulfur cathode in the form of a unique bamboo-shaped structured nanofiber, using SPAN as the bamboo stalk and reduced graphene oxide (rGO) as the bamboo joint, thus ensuring that the SPAN has excellent electronic conductivity. Polyacrylonitrile grafted with rGO (PAN-g-rGO) is an effective composite of ultra-high molecular weight PAN (UHMW PAN) and rGO at the molecular level. The UHMW PAN precursor can provide high sulfur loading, and the bamboo joint-like rGO can offer short-range accelerated electron transfer, thus effectively enhancing the electrochemical performance of the battery. Sulfurized PAN-g-rGO fiber (SFPAN-g-rGO) with a sulfur content of approximately 53 wt% is fabricated using PAN-g-rGO with a molecular weight of 3.6 × 105 Da as the precursor. The battery has a high reversible specific capacity (1463 mAh g−1 at 0.2C), excellent C-rate performance (1239 mAh g−1 at 2C), and good cycling stability (guaranteed over 800 cycles). In addition, the electrode offers a high reversible specific capacity of 1383 mAh g−1 at 0.1C and 1280 mAh g−1 at 0.2C when tested under a lean electrolyte (E/S: 10 μL mg−1) and high mass loading (4.8 mg cm−2), thus illustrating its good development potential.