A free-standing sulfide polyacrylonitrile/reduced graphene oxide film cathode with nacre-like architecture for high-performance lithium-sulfur batteries

Abstract

Sulfide polyacrylonitrile (SPAN) is regarded as a promising cathode material to replace traditional carbon/sulfur composites, due to its conversion solid-solid transformation mechanism that effectively eliminates the shuttle effect of lithium sulfur batteries (LSBs). Unfortunately, its low sulfur content and slow reaction kinetics greatly affect the electrochemical performance. In this paper, a scalable production method is developed to fabricate free-standing sulfide polyacrylonitrile/reduced graphene oxide (SPAN/RGO) film cathode with nacre-like architecture. In this novel free-standing film cathode, graphene nanosheets act as a stable conductive framework and SPAN nanoparticles evenly disperse between the graphene nanosheets. The dense layered structure effectively alleviates the volume expansion of sulfur during cycling. Ex-situ Raman analysis provides evidence for the reversible cleavage and reformation of C−S/S−S bonds throughout the charge-discharge cycle. With these advantages, free-standing SPAN/RGO film cathode exhibits a low-capacity decay rate of 0.052 % over 1000 cycles at 0.5 C. Additionally, it maintains stable cycling performance even when the SPAN loading reaches 10.0 mg cm⁻². This offers a straightforward and effective approach for the development of practical cathode materials for lithium-sulfur batteries (LSBs).