Effect of Additives on the Dispersion Properties of Aqueous Based C/LiFePO4 paste and its Impact on Lithium Ion Battery High Power Properties

Abstract

Aqueous-based C/LiFePO4 positive electrodes with high-rate capabilities are described with an intended application in lithium ion batteries. Pastes consisting of C/LiFePO4 particles, sodium carboxymethyl cellulose (CMC), water-soluble elastomeric binder (WSB) and poly (acrylic acid) (PAA) were prepared in an aqueous medium and tape-cast onto an aluminum foil. It was found that the incorporation of PAA significantly decreased the apparent viscosity of the C/LiFePO4 paste as well as shifted particle size distribution to lower value, which resulted in an improvement of the C/LiFePO4 dispersion properties. A correlation was made between the dispersion properties and the electrochemical properties. The electrochemical properties indicated that the electrode with PAA exhibited a discharge specific capacity above 70 mAhg(-1) at 20C, which was about seven times higher than the discharge specific capacity without PAA at 20C which showed a discharge specific capacity of only 10 mAhg(-1). This was attributed to the formation of a resistance-imparting agglomeration, which is consistent with the dispersion properties of C/LiFePO4 particles.