Phosphorus-sulfur/graphene composites as flexible lithium-sulfur battery cathodes with super high volumetric capacity

摘要

A phosphorus-sulfur/graphene composite (PS/G composites) cathode via a one-step PS additive reaction at 320 degrees C is reported to achieve high volumetric capacities with a high sulfur packing density. The PS/G composites are self-supporting, bendable, and compressible, and can be easily compressed into a sheet of binder-free LiS cathode. The PS/G cathode with an extremely high cathode sulfur density of 1.8 g cm(-3) (active materials content of 80%) delivers an excellent specific capacity of 959 mA h g(-1), an areal capacity of 5.5 mA h cm(-2), and exhibits a low capacity fading rate (0.15% per cycle) within 200 cycles (similar to 60% utilization). Consequently, the electrode gives a corresponding high volumetric capacity of 1726 mA h cm(-3) (the volume is based on all cathode materials plus current collector). Moreover, flexible devices of Li-S pouch cell using PS/G composites as cathodes shows stable electrochemical characteristics under bending condition, demonstrating their feasibility in commercial batteries.