title: Increasing the Affinity Between Carbon-Coated LiFePO4/C Electrodes and Conventional Organic Electrolyte by Spontaneous Grafting of a Benzene-Trifluoromethylsulfonimide Moiety.
abstract: The grafting of benzene-trifluoromethylsulfonimide groups on LiFePO4/C was achieved by spontaneous reduction of in situ generated diazonium ions of the corresponding 4-amino-benzene-trifluoromethylsulfonimide. The diazotization of 4-amino-benzene-trifluoromethylsulfonimide was a slow process that required a high concentration of precursors to promote the spontaneous grafting reaction. Contact angle measurements showed a hydrophilic surface was produced after the reaction that is consistent with grafting of benzene-trifluoromethylsulfonimide groups. Elemental analysis data revealed a 2.1 wt % loading of grafted molecules on the LiFePO4/C powder. Chemical oxidation of the cathode material during the grafting reaction was detected by X-ray diffraction and quantified by inductively coupled plasma atomic emission spectrometry. Surface modification improves the wettability of the cathode material, and better discharge capacities were obtained for modified electrodes at high C-rate. In addition, electrochemical impedance spectroscopy showed the resistance of the modified cathode was lower than that of the bare LiFePO4/C film electrode. Moreover, the modified cathode displayed superior capacity retention after 200 cycles of charge/discharge at 1 C.
authors.affiliation: Département de Chimie, Université du Québec à Montréal , Case Postale 8888, succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Delaporte
authors.affiliation: Département de Chimie, Université du Québec à Montréal , Case Postale 8888, succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8.
authors.forename: Alexis
authors.initials: A
authors.lastname: Perea
authors.affiliation: Département de Chimie, Université du Québec à Montréal , Case Postale 8888, succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8.
authors.forename: Estelle
authors.initials: E
authors.lastname: Lebègue
authors.affiliation: Institut de Recherche d'Hydro-Québec (IREQ) , 1800 Boulevard Lionel Boulet, Varennes, Québec, Canada J3X 1S1.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ladouceur
authors.affiliation: Institut de Recherche d'Hydro-Québec (IREQ) , 1800 Boulevard Lionel Boulet, Varennes, Québec, Canada J3X 1S1.
authors.forename: Karim
authors.initials: K
authors.lastname: Zaghib
authors.affiliation: Département de Chimie, Université du Québec à Montréal , Case Postale 8888, succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bélanger
keywords: cathode; in situ generated aryl diazonium; lithium-ion battery; olivine; surface modification; wettability