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Article

Protection of LiFePO4 against Moisture

1
Département de Chimie, Université du Québec à Montréal, Case Postale 8888, succursale Centre-Ville, Montréal, QC H3C 3P8, Canada
2
Institut de Recherche d’Hydro-Québec (IREQ), 1800 Boulevard Lionel Boulet, Varennes, QC J3X 1S1, Canada
*
Authors to whom correspondence should be addressed.
Materials 2020, 13(4), 942; https://doi.org/10.3390/ma13040942
Received: 22 January 2020 / Revised: 11 February 2020 / Accepted: 18 February 2020 / Published: 20 February 2020
(This article belongs to the Section Energy Materials)
In this study, a carbon-coated LiFePO4 (LFP/C) powder was chemically grafted with trifluoromethylphenyl groups in order to increase its hydrophobicity and to protect it from moisture. The modification was carried out by the spontaneous reduction of in situ generated 4-trifluoromethylphenyl ions produced by the diazotization of 4-trifluoromethylaniline. X-ray photoelectron spectroscopy was used to analyze the surface organic species of the modified powder. The hydrophobic properties of the modified powder were investigated by carrying out its water contact angle measurements. The presence of the trifluoromethylphenyl groups on the carbon-coated LiFePO4 powder increased its stability in deionized water and reduced its iron dissolution in the electrolyte used for assembling the battery. The thermogravimetric and inductively coupled plasma atomic emission spectroscopy analyses revealed that 0.2–0.3 wt.% Li was deinserted during grafting and that the loading of the grafted molecules varied from 0.5 to 0.8 wt.% depending on the reaction conditions. Interestingly, the electrochemical performance of the modified LFP/C was not adversely affected by the presence of the trifluoromethylphenyl groups on the carbon surface. The chemical relithiation of the grafted samples was carried out using LiI as the reducing agent and the lithium source in order to obtain fully lithiated grafted powders. View Full-Text
Keywords: surface modification; trifluoromethylaniline; diazonium; grafting; hydrophobic powder; olivine; cathode; Li-ion surface modification; trifluoromethylaniline; diazonium; grafting; hydrophobic powder; olivine; cathode; Li-ion
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MDPI and ACS Style

Delaporte, N.; Trudeau, M.L.; Bélanger, D.; Zaghib, K. Protection of LiFePO4 against Moisture. Materials 2020, 13, 942. https://doi.org/10.3390/ma13040942

AMA Style

Delaporte N, Trudeau ML, Bélanger D, Zaghib K. Protection of LiFePO4 against Moisture. Materials. 2020; 13(4):942. https://doi.org/10.3390/ma13040942

Chicago/Turabian Style

Delaporte, Nicolas; Trudeau, Michel L.; Bélanger, Daniel; Zaghib, Karim. 2020. "Protection of LiFePO4 against Moisture" Materials 13, no. 4: 942. https://doi.org/10.3390/ma13040942

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