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Development of new catalytic function by surface fluorination of graphite

石墨表面氟化开发新催化功能

基本信息

批准号：
10650826
负责人：
NAKAJIMA Tsuyoshi
金额：
$ 1.92万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650826/
关键词：
Surface fluorination Intercalation Lithium ion battery Carbon anode フッ素化反応

项目摘要

Surface fluorination of graphite powder with average diameters, 7, 25 and 40 μm has been made by elemental fluorine at 80-520℃, and the electrochemical intercalation and deintercalation of lithium ion has been investigated in 1 mol dmィイD1-3ィエD1 LiClOィイD24ィエD2 ethylene carbonate/diethyl carbonate (1:1) solution. Fluorine contents were less than ca. 2 at% by elemental analysis and surface fluorine concentrations obtained by XPS were 6〜15 at%. Carbon-fluorine bonding is intermediate between the ionic and covalent, approaching the covalent bond with increasing fluorination temperature. Raman spectroscopy revealed that surface disorder is increased by fluorination. Graphite samples with average diameters 7, 25, 40 μm have the reversible capacities of 360, 350 and 330 mAhgィイD1-1ィエD1, respectively at 60 mAgィイD1-1ィエD1, however all the fluorinated samples have shown the larger capacities of 380〜400 mAhgィイD1-1ィエD1 than the theoretical value 372 mAhgィイD1-1ィエD1. The capacity and reaction rate increase would be due to increase in surface areas and formation of surface pores for lithium accumulation.NMR study on C-F bonding has indicated that carbon-fluorine bond is ionic in the region of x>8 in CィイD2xィエD2F and semi-ionic nature increases with decreasing x. Addition of fluoroester and fluoroether to EC/DEC increases the reversible capacities of graphite electrode.

在80-520℃下，用氟对平均粒径为7、25和40 μm的石墨粉进行表面包覆，并在1 mol dm-3的碳酸亚乙酯/碳酸二乙酯（1：1）溶液中研究了锂离子的电化学嵌脱。氟含量均小于ca。通过元素分析得到的表面氟浓度为2at%，通过XPS得到的表面氟浓度为6at%~ 15at%。碳-氟键是离子键和共价键之间的中间键，随着温度的升高而接近共价键。拉曼光谱表明，表面无序度增加，由纳米。平均直径为7、25、40 μm的石墨样品在60 mAg/cm 2 D1 -1 μ m D1下的可逆容量分别为360、350和330 mAhg/cm 2 D1 - 1 μ m D1，然而所有氟化样品均显示出380 - 400 mAhg/cm 2 D1-1 μ m D1的较大容量，而理论值为372 mAhg/cm 2 D1-1 μ m D1。C-F键的NMR研究表明，在C_xD_2x_xD_2F中，当x>8时，碳-氟键是离子键，随着x的减小，半离子键的性质增强。在EC/DEC中加入氟代酯和氟代醚可提高电极的可逆容量。