CO 2 -Activation Nanofiber Carbon Paper as a High-Performance Interlayer for Trapping Polysulfides in Li-S Batteries.

Lithium-sulfur (Li-S) batteries have high theoretical energy density but low sulfur utilization due to the inherent insulating nature of sulfur and the shuttle effect of polysulfides. Herein, the CO 2 -activation carbon paper was prepared by poly( p -phenylenebenzobisoxazole) (PBO) nanofiber and was first applied as an interlayer for efficiently alleviating the shuttle effect of polysulfides in Li-S batteries. This interlayer exhibits good flexibility and strength with rich -C═O and -COOH functional groups on the three-dimensional porous structure, which improves chemical adsorption on Li 2 S x species and ion rapid diffusion via interconnected diffusion channels and thus enhances the electrochemical kinetics. The initial specific capacity is 1367.4 mAh g -1 and remains 999.8 mAh g -1 after 200 cycles at 0.2C and 780.1 mAh g -1 at 5C, and the Coulombic efficiency is high, up to 99.8%, which is much better than that for the carbon paper without CO 2 activation. The highly conductive flexible PBO carbon paper may bring breakthroughs in performance and thus lead to more practical applications of Li-S batteries.