Hierarchical Nanostructured Carbon/Sulfur Hybrid Cathode for High-Performance Lithium-Sulfur Battery

Wednesday, 11 June 2014
Cernobbio Wing (Villa Erba)
H. J. Peng (Beijing Key Laboratory of Green Reaction Engineering and Technology, Tsinghua University, P. R. China), J. Q. Huang (Department of Chemical Engineering, Tsinghua University, Beijing, P. R. China), M. Q. Zhao (Department of Materials Science and Engineering, Drexel Univerisity, Philadelphia, USA), Q. Zhang (Tsinghua University), X. Y. Liu, and F. Wei (Department of Chemical Engineering, Tsinghua University, Beijing, P. R. China)
Among various energy storage/conversion systems, lithium-sulfur batteries are considered as one of the most promising candidate due to not only very high theoretical energy density of 2600 Wh kg-1 (based on lithium-sulfur redox couple) and wide operating temperature range benefiting from its unique multiple-electron-transfer chemistry, but also abundant reserves and environmental friendliness of sulfur. However, several intrinsic obstacles should be overcome for its applicably extension, including the ultra-low electrical conductivity of sulfur and its lithiated products, huge volumetric changes during charge and discharge, and the shuttling mechanism of soluble intermediate polysulfides.

Here, a hierarchical nanostructured carbon/sulfur hybrid in which the porous carbon was in situ integrated into graphene/single-walled carbon nanotube (SWCNT) hybrid matrix with small cyclo-S8 molecule clusters was fabricated as advanced cathode material for lithium-sulfur battery application. The sp2 graphene/SWCNT hybrid interlinked framework was served as robust conductive scaffold with good electrical conductivity and structure stability, while the micro-/mesoporous carbon accommodated sulfur and lithium polysulfides, provided accessibility for liquid electrolyte to active material, and suppress the shuttle behavior due to the spacial confinement. Therefore, such hierarchical all-carbon nanostructure hybridized with small cyclo-S8 molecule clusters obtained an excellent electrochemical performance including an ultrahigh specific capacity of 1121 mAh g-1 at 0.5 C, a favorable high-rate capability of 809 mAh g-1 at 10 C, a very low capacity decay of 0.12 % per cycle, and an impressive cycling stability of 877 mAh g-1 after 150 cycles at 1 C. As sulfur loading increasing from 50 wt % to 77 wt %, high capacities of 970, 914, and 613 mAh g-1 were still available at current densities of 0.5, 1, and 5 C respectively. Based on the total mass of packaged devices, gravimetric energy density of GSH@APC-S//Li cell was expected to be 400 Wh kg-1 at a power density of 10000 W kg-1, matching the level of engine driven systems.


[1] HJ Peng, et al. Adv. Funct. Mater., 2014, DOI: 10.1002/adfm.201303296