Self-supported 3D Aerogel Network Lithium Sulfur Battery Cathode: Sulfur Spheres Wrapped with Phosphorus Doped Graphene and Bridged with Carbon Nanofibers
Practical applications of lithium sulfur batteries have been impeded by its poor cycling stability that results from the “shuttling” of polysulfides. Herein, we demonstrate a new strategy for developing hierarchical phosphorus-doped graphene/carbon nanofibers/sulfur aerogel (PGCNF/S) with “network” morphologies, in which the sulfur spheres are wrapped by the graphene sheets and carbon nanofibers (PGCNF) with “net” structures and this carbon matrix has greatly improved the electrochemical performances of sulfur spheres. PGCNF nets ensure a uniform loading of sulfur spheres that leads to a high sulfur mass loading of 85 wt.%. Also, the good porous structures achieved by this PGCNF/S cathode can provide sufficient space for volume expansion of active sulfur spheres. Due to its structural advantages, this binder-free PGCNF/S cathode exhibits a specific capacity of 1360 mAh g-1 at 0.1 C, and a high areal capacity of 21.5 mAh cm-2 based on a high sulfur mass loading of 15.8 mg cm-2. Furthermore, a long term cycling stability of 600 times has been achieved by this PGCNF/S cathode with an average Coulombic efficiency of ~ 99.8%. This work highlights a broadly adaptable strategy of “network” structure for developing scalable and high-energy density electrode materials for energy storage devices.