title: Free-standing nitrogen-doped graphene paper as electrodes for high-performance lithium/dissolved polysulfide batteries.
abstract: Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping.
authors.affiliation: College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 (P.R. China); Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, 60208 (United States).
authors.forename: Kai
authors.initials: K
authors.lastname: Han
authors.forename: Jingmei
authors.initials: J
authors.lastname: Shen
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Hao
authors.forename: Hongqi
authors.initials: H
authors.lastname: Ye
authors.forename: Christopher
authors.initials: C
authors.lastname: Wolverton
authors.forename: Mayfair C
authors.initials: MC
authors.lastname: Kung
authors.forename: Harold H
authors.initials: HH
authors.lastname: Kung
mesh_terms: D011211:Electric Power Supplies; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D010209:Paper; D013440:Sulfides / Q000737:chemistry*
chemical_list: D013440:Sulfides; D006108:Graphite; C032915:polysulfide; D008094:Lithium; D009584:Nitrogen
keywords: Li/polysulfide battery; N-doped graphene; binder-free; catholyte; free-standing