Electrochemical characterization of the LiCoO2/acetylene carbon ratios for porous electrodes in alkaline lithium aqueous solutions by electrochemical impedance spectroscopy

LiCoO2 electrodes were fabricated with different acetylene carbon (AC) additions and fixed binder content. Subsequent electrochemical testing showed different processes at the interface that are related to pore distribution and electrode composition. Electrochemical impedance spectroscopy characterized the mechanisms close to open circuit conditions. The active state, combined with diffusion mechanisms within the cylindrical pores, contributed to the functionality of the particles according to the LiCoO2/AC content, and surface characteristics of the electrode influenced the impedance distribution. The de Levie theory for porous electrode was used to describe the influence of the LiCoO2/AC ratios in the impedance distribution when exposed to alkaline aqueous electrolytes (LiOH + Li2SO4). The pore model helped relate physical properties of the composite material, such as pore count, pore length, and double layer capacitance, with the mechanisms present at the interface. The theoretical model was validated with experimental data and the fitting process resulted in good agreement. (C) 2010 Elsevier Ltd. All rights reserved.