(616g) Free-Standing Sulfur/Carbon Nanofibers Film As a Cathode for Lithium-Sulfur Battery

Lithium-sulfur (Li-S) batteries are regarded as a promising next-generation electrical-energy-storage technology due to their low cost and high theoretical energy density. Furthermore, flexible and wearable electronics urgently requires their power sources to be mechanically robust and flexible. However, the effective progress of high-performance, flexible Li-S batteries is still hindered by the poor conductivity of sulfur cathodes and the dissolution of lithium polysulfides as well as the weak mechanical properties of sulfur cathodes.

Herein, we demonstrate a novel strategy to prepare flexible and free-standing sulfur cathode with improved mechanical strength, the matrix of the free-standing sulfur cathode is constructed from graphitized nitrogen-doped mesoporous carbon nanofibers (NPCFs). Benefiting from the unique micro/mesoporous structure and highly graphitic carbon, the NPCFs film are capable of accommodating more sulfur, and maintain substantially higher mechanical strength and flexibility after sulfur loading as compared with the traditional microporous carbon nanofiber film. As a free-standing and flexible cathode for Li-S batteries, the robust composite film exhibits high rate capability with 540 mA h g-1 at 5 C, and excellent cycling stability (could maintain 76.5% capacity after 500 cycles at 5 C).