Loadings of Functionalized Multiwalled Carbon Nanotubes for Enhancing Sulfurized Polyacrylonitrile Performance in Lithium–Sulfur Batteries

Abstract

Due to its distinctive solid–solid reaction mechanism, sulfurized polyacrylonitrile (SPAN) has emerged as a promising cathode material for lithium–sulfur batteries (LiSBs). However, SPAN inherits the poor conductivity of sulfur (S), necessitating its combination with conductive carbon nanomaterials, such as carbon nanotubes during utilization. The weak interfacial interactions of carbon nanotubes hinder their uniform dispersion within the polymer matrix, thereby severely compromising the electrochemical performance of LiSBs. Consequently, this study employs computational simulations and experimental investigations to examine the dispersion behavior of functionalized multiwalled carbon nanotubes (FMWCNTs) within a polyacrylonitrile (PAN) matrix and subsequently elucidates their impacts on electrochemical performance. The simulation calculations and dispersion experiments collectively indicate that aminated multiwalled carbon nanotubes, possessing lower mixing free energy and the closest Hansen solubility parameters to PAN, exhibit optimal dispersion characteristics. The initial discharge capacities at rates of 0.2 and 1.0C are 907.4 and 843.4 mAh g–1, respectively, which surpass the theoretical predictions. Following 400 cycles, a negligible capacity decay is observed. The favorable dispersion enhances the electrochemical performance of the battery. This investigation provides insights into optimizing the design of PAN and carbon nanomaterials to elevate the electrochemical performance of LiSBs.