Polysulfide Trapping in Carbon Nanofiber Cloth/S Cathode with a Bifunctional Separator for High-Performance Li-S Batteries.

The development of carbon nanofiber (CNF) cloth-based cathodes is essential for the fabrication of high energy density and flexible Li-S batteries. Surface modification is generally used to improve the electrochemical performance of CNF cloth/S cathodes. However, this strategy creates some problems such as structure collapse, complex fabrication steps, and poor consistency. Herein, a β-MnO2 nanowire/graphene-modified separator is used to improve the performance of CNF cloth/S cathodes without changing their structure. β-MnO2 can facilitate chemical bonding with polysulfides, whereas graphene can decrease the inner resistance and trap polysulfide by physical shielding. The cathode with the bifunctional separator displayed a high discharge capacity of 529.9 mAh g-1 with a low capacity decay of 0.051 % per cycle after 500 cycles at 1 C, which is 3 times higher compared with a bare separator. Even with a high sulfur loading of 9.0 mg cm-2 , a high areal capacity of 3.8 mAh cm-2 was delivered over 100 cycles.