title: Lithium-sulfur batteries based on nitrogen-doped carbon and an ionic-liquid electrolyte.
abstract: Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic-liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide ([MPPY][TFSI]) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the lower onset sulfur reduction potential, higher redox current density in the CV test, and faster charge-transfer kinetics, as indicated by EIS measurements. At room temperature under a current density of 84 mA g(-1) (C/20), the battery based on the NC/S composite exhibited a higher discharge potential and an initial capacity of 1420 mAh g(-1), whereas the battery based on the AC/S composite showed a lower discharge potential and an initial capacity of 1120 mAh g(-1). Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; capacity fading can be improved by further cathode modification.
authors: Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA. sunx@ornl.gov
authors: Xiao-Guang
authors: XG
authors: Sun
authors: Xiqing
authors: X
authors: Wang
authors: Richard T
authors: RT
authors: Mayes
authors: Sheng
authors: S
authors: Dai
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004553:Electric Conductivity; D011211:Electric Power Supplies; D004563:Electrochemistry; D052578:Ionic Liquids / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D016062:Porosity; D013455:Sulfur / Q000737:chemistry*
chemical_list: D052578:Ionic Liquids; D013455:Sulfur; D002244:Carbon; D008094:Lithium; D009584:Nitrogen