Heteroatom-doped Graphene Nanotubes as Carbon Host Materials for High-Performance Lithium-Sulfur Batteries
MetadataShow full item record
In order to further increase the boundaries of energy storage, new battery chemistries must be explored with higher theoretical capacities than that of conventional lithium-ion batteries. Lithium-sulfur batteries have shown promise for enhanced energy density and discharge capacities which could lead to a huge shift in commercialized battery technologies. This work attempts to address some of the performance-related issues of lithium-sulfur batteries by retaining the long-chain polysulfide intermediates on the cathode via heteroatom-doping of the carbon host structure. Herein, we report nitrogen and transition metal doped graphene nanotubes (M-GNTs) which were utilized as carbon host structures for sulfur (M-GNTs@S) to be used as a cathode material for lithium-sulfur batteries. The top performing M-GNTs@S are nitrogen, cobalt, nickel, and iron doped (FCN-GNTs). The nitrogen and metal dopants are effective in increasing the kinetics of the lithium-sulfur batteries, enhancing rate capability, and increasing cycle lifetime at C/5 and 1C. The FCN-GNT material exhibits a 554.4 mAh g-1 discharge capacity after 500 cycles at 1C (0.08% capacity loss per cycle). In addition, a high areal sulfur loading (~4.5 mg S cm-2) was achieved leading to discharge capacities of 1234.7 mAh g-1 (5.52 mAh cm-2) at C/20 and 909.0 mAh g-1 (4.07 mAh cm-2) at C/5. After ten cycles at C/5, the ultra-high sulfur loading cells discharged 828.0 mAh g-1 (3.70 mAh cm-2).