碳纳米管
材料科学
锂(药物)
离子
电化学
穆斯堡尔谱学
碳纤维
化学工程
复合材料
阳极
色散(光学)
结晶
化学
复合数
电极
物理化学
有机化学
医学
工程类
内分泌学
作者
Magali Brisbois,Sébastien Caes,Moulay Tahar Sougrati,Bénédicte Vertruyen,Audrey Schrijnemakers,Rudi Cloots,Nicolas Eshraghi,Raphaël P. Hermann,Abdelfattah Mahmoud,Frédéric Boschini
出处
期刊:Le Centre pour la Communication Scientifique Directe - HAL - Diderot
日期:2016-04-01
被引量:25
标识
DOI:10.1016/j.solmat.2015.09.005
摘要
Abstract In order to favor electronic conductivity in sodium iron fluorophosphate electrodes for lithium- or sodium-ion batteries, composites of Na2FePO4F with multi-walled carbon nanotubes (CNTs) were prepared by pilot-scale spray drying. Addition of multi-walled CNTs in the solution results in an excellent dispersion of the CNTs within the volume of Na2FePO4F and not only at the surface of the particles. Following a heat treatment at 600 °C in argon in order to reach crystallization, X-ray diffraction and ex situ Mossbauer spectroscopy revealed the presence of significant amounts of Fe(III) and maghemite (γ-Fe2O3) in the powder. However, Na2FePO4F/CNTs composites exhibit good electrochemical performance when cycling against lithium, with a discharge capacity of 104 mA h g−1 at C/10 rate and 90 mA h g−1 at 1C rate. Therefore, operando 57Fe transmission Mossbauer spectroscopy analyses were carried out in order to investigate the evolution of the iron oxidation state during cycling. During the first discharge, all the Fe(III) is reduced to Fe(II), explaining the good electrochemical performance.
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