▎ 摘　　要

Graphene-like N,S-codoped bio-carbon nanosheets (GNSCS) were prepared by a facile and environment-friendly NaCl non-aqueous ionic liquid route to house sulfur for lithium-sulfur battery. The natural nori powder was calcined at 900 degrees C for 3 h under Ar, in which NaCl non-aqueous ionic liquid can exfoliate carbon aggregates into nanosheets. The structural characterization of GNSCS by a series of techniques demonstrates the graphene-like feature. When evaluated as the matrix for sulfur cathode, GNSCS/S exhibits more prominent cycling stability and rate capability. A discharge capacity of 548 mA h g(-1) at a current density of 1.6 A g(-1) after 400 cycles was delivered with a capacity fade rate of only 0.13% per cycle and an initial Coulombic efficiency (CE) as high as 99.7%. When increasing the areal sulfur loading up to 3 mg cm(-2), the discharge capacity can still be retained at 647 mA h g(-1) after more than 100 cycles with a low capacity degradation of only similar to 0.30% per cycle. The features of N/S dual-doping and the graphene-like structure are propitious to the electron transportation, lithium-ion diffusion and more active sites for chemically adsorbing polysulfides. It is anticipated that other functional biochar carbon can also be attained via the low-cost, sustainable and green method.