摘要
The dispersion property of aqueous lithium cobalt oxide (LiCo O2) slurries and their corresponding cell performance with and without addition of dispersant, ammonium polyacrylic acid (PAA-N H4), were investigated. The surface chemical properties of LiCo O2 and graphite powders were characterized by diffuse reflectance using infrared Fourier transform spectrometry. The adsorption effects of PAA-N H4 and latex binder (LA132), respectively, on the dispersion behaviors of LiCo O2 and graphite powders in aqueous suspensions were analyzed by measurements of adsorption behavior, ζ potential, sedimentation property, and rheology. The results showed that the PAA-N H4 can adsorb onto both the LiCo O2 and graphite powders to stabilize them in aqueous suspensions, but LA132 binder only adsorbs onto graphite and showed a competitive adsorption with PAA-N H4 on the graphite surface. By observation of scanning electron microscope, it was shown that the as-prepared LiCo O2 sheet without PAA-N H4 addition had significant agglomeration of powders and accumulation of binder around the powder. These undesired coagulations of powder and binder can be diminished by increasing the PAA-N H4 content. Although the dispersion property of powders was increased with increasing PAA-N H4 content, too much addition of PAA-N H4 is detrimental to the electronic conduction, adhesion strength, and electrochemical properties of LiCo O2 electrode. To simultaneously obtain a well-dispersed and a better electrochemical property of LiCo O2 electrode sheet, the appropriate amount of PAA-N H4 was found to be on the order of 0.01 wt % based upon LiCo O2. © 2005 The Electrochemical Society. All rights reserved.