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Lithium–Sulfur Batteries Based on Nitrogen‐Doped Carbon and an Ionic‐Liquid Electrolyte
Author(s) -
Sun XiaoGuang,
Wang Xiqing,
Mayes Richard T.,
Dai Sheng
Publication year - 2012
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200101
Subject(s) - polysulfide , ionic liquid , cyclic voltammetry , electrolyte , lithium–sulfur battery , cathode , dielectric spectroscopy , electrochemistry , composite number , inorganic chemistry , chemistry , sulfur , materials science , chemical engineering , electrode , organic chemistry , composite material , catalysis , engineering
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.