Nitrogen/sulfur co-doping for biomass carbon foam as superior sulfur hosts for lithium-sulfur batteries

Summary To address volume expansion from active sulfur and shuttle effect from polysulfides during the electrochemical process of lithium sulfur batteries, nitrogen/sulfur co-doping porous active carbons (NS-PACs) derived from biomass cattail were manufactured by one-step activated hydrothermal method. The effects of N/S atoms co-doping and the activation of KOH on NS-PACs were investigated in the macro-morphology, micro-structure, and electrochemical performance using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), as well as galvanostatic charge/discharge tests. The experimental data demonstrated that the NS-PACs show stable foam-likes porous structure, and the specific surface area (SSA) and pore volumes are 2155.81 m 2 g −1 and 1.43 cm 3 g −1 , respectively, and reveals perfect N/S atoms doping with S atomic content of 1.4% and N atomic content of 0.78%. Moreover, the initial discharge capacity of NS-PACs is 1477.8 mAh g −1 at 0.1 C and the extraordinary long-run cycling stability after 500 cycles reaches 803.4 mAh g −1 at 2.0 C. These outstanding electrochemical performances of NS-PACs are associated with efficient physical confinement by porous architecture together with the potent chemical adsorption of N/S atoms with polysulfide.