A High-Volumetric-Capacity Cathode Based on Interconnected Close-Packed N-Doped Porous Carbon Nanospheres for Long-Life Lithium–Sulfur Batteries

4 years ago

A High-Volumetric-Capacity Cathode Based on Interconnected Close-Packed N-Doped Porous Carbon Nanospheres for Long-Life Lithium–Sulfur Batteries

Carlos Cuadrado-Collados, Caroline Kirk, Joaquín Silvestre-Albero, Qiong Cai, Mark James Biggs, Francisco Rodríguez-Reinoso, Cheng Hu

This study reports a Li–S battery cathode of high volumetric capacity enabled by novel micro- and mesostructuring. The cathode is based on monodisperse highly porous carbon nanospheres derived from a facile template- and surfactant-free method. At the mesoscale, the nanospheres structure into interconnected close-packed clusters of a few microns in extent, thus facilitating the fabrication of dense crack-free high areal sulfur loading (5 mg cm−2) cathodes with high electrical conductivity and low cathode impedance. A combination of the nitrogen doping (5 wt%), high porosity (2.3 cm3 g−1), and surface area (2900 m2 g−1) at the microscale enables high sulfur immobilization and utilization. The cathode delivers among the best reported volumetric capacity to date, above typical Li-ion areal capacity at 0.2 C over 200 cycles and low capacity fading of 0.1% per cycle at 0.5 C over 500 cycles. The compact cathode structure also ensures a low electrolyte requirement (6 µL mg−1), which aids a low overall cell weight, and further, among the best gravimetric capacities published to date as well. Li–S battery cathodes providing among the best volumetric/gravimetric capacities reported to date are prepared using interconnected close-packed N-doped carbon nanospheres of high surface area and porosity. The novel close-packed mesostructure and N-doped highly porous microstructure enable simultaneously high sulfur density and utilization, excellent electrochemical impedance, long cycle-life, and low electrolyte fraction, which all-together leads to the outstanding volumetric/gravimetric capacities.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/aenm.201701082