Porous 3D nitrogen-doped rGO/Co-Ni-S composite modified separator for high-capacity and stable lithium-sulfur batteries

Abstract A porous composite material consisted of nitrogen-doped 3D reduced graphene oxide and evenly distributed cobalt-nickel-sulfur (CNS) nanoparticles was coated on the surface of separator serving as the interlayer between separator and electrode in lithium-sulfur battery. It delivered an initial discharge capacity of 1524 mAh g−1 at 0.1 C and a discharge capacity of 610 mAh g−1 at 8 C. The designed Li-S battery exhibited superior long-term stability. After 350 cycles tested at 1 C, it retained a capacity as high as 700 mAh g−1. It revealed that the N-dopants and decorated CNS nanoparticles in the composite could provide active sites to adsorb soluble polysulfides and accelerate the conversion of polysulfides in redox reactions, respectively, thereby suppressing the shutter effect and improving the electrochemical performance of the Li-S battery. Our strategy is promising for preparing safe and long-cycle Li-S batteries.