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

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.C.H. acknowledges a Postdoctoral Fellowship provided by Loughborough University. Dr. Zhaoxia Zhou at Loughborough Materials Characterization Centre, Loughborough University is gratefully acknowledged for assistance with the TEM work. Q.C. gratefully acknowledges the support by the EPSRC program EP/M027066/1