Collect. Czech. Chem. Commun. 2008, 73, 1693-1704

Electrochemical Properties of Surface-Fluorinated Vapor Grown Carbon Fiber for Lithium Ion Battery

Tsuyoshi Nakajimaa,*, Ken-ichi Hashimotoa, Takashi Achihaa, Yoshimi Ohzawaa, Akira Yoshidab, Zoran Mazejc, Boris Žemvac, Young-Seak Leed and Morinobu Endoe

a Department of Applied Chemistry, Aichi Institute of Technology, Yaskusa, Toyota 470-0392, Japan
b Faculty of Engineering, Musashi Institute of Technology, 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo 158-8557, Japan
c Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
d School of Chemical Engineering, Chungnam National University, Tajeon 305-764, Korea
e Department of Electrical and Electronic Engineering, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380-8553, Japan


Surface fluorination of graphitized vapor grown carbon fiber (VGCF) has been performed with F2, F2-O2, NF3 or ClF3 under mild conditions. Charge/discharge characteristics were investigated in 1 mol/l LiClO4-ethylene carbonate (EC)/diethyl carbonate (DEC) and EC/DEC/ propylene carbonate (PC) solutions. The main effect of surface fluorination was increase in charge capacities. The increase in charge capacities was larger for VGCF fluorinated with ClF3 or NF3 than F2 or F2-O2. The reason is that the fluorination reactions of graphite with ClF3 and NF3 are radical reactions having surface etching effect, effectively breaking cylindrically rolled graphene layers of VGCF.

Keywords: Surface modification; Chemical vapor deposition; Fluorination; Graphite anode; Lithium ion battery; Carbon electrodes.

References: 57 live references.