Freestanding porous sulfurized polyacrylonitrile fiber as a cathode material for advanced lithium sulfur batteries

A freestanding porous sulfurized polyacrylonitrile/vapor grown carbon fiber (SVF) composite was prepared as cathode material for high-performance lithium sulfur batteries by a facile electrospinning technique. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability with the property of flexibility, essential to the development of flexible batteries. The capacity retentions of the SVF cell were 903 mAh g−1 after 150 cycles at 1 C and 600 mAh g−1 after 300 cycles at 2 C. At a high rate of 4 C, the SVF composite showed reasonable capacity retention. The superior performance of SVF composite was attributed to the highly porous structure, which effectively improved the wettability, accessibility, and absorption of electrolyte to facilitate rapid ion transfer in the cell. Vapor-grown carbon fibers embedded inside SVF as a carbon material notably enhanced the electrical conductivity of the cell, guaranteeing the electrochemical performance at high C-rates. The freestanding porous SVF fiber composite is a promising cathode material for advanced flexible lithium sulfur batteries.