Electrochemical impedance study of Li-ion insertion into mesocarbon microbead single particle electrode Part II. Disordered carbon

Electrochemical impedance spectroscopy (EIS) was applied for a single mesocarbon microbead (heat-treated at 1000 degreesC) of 30 mum diameter during Li-ion insertion and extraction using a stainless tip-microelectrode in the electrolyte of 1 M LiClO4/propylene carbonate + ethylene carbonate. Obtained spectra were analyzed with an equivalent circuit model. Kinetic parameters such as the charge transfer resistance, and the apparent chemical diffusion coefficient of Li-ion in the particle were evaluated without interference of organic binders, The charge transfer resistance decreased and chemical diffusion coefficient of Li-ion increased as the electrode potential was made more negative. The chemical diffusion coefficient varied within 10(-12)-10(-6) cm(2) s(-1). (C) 2001 Elsevier Science Ltd. All rights reserved.