Dispersion properties of aqueous-based LiFePO4 pastes and their electrochemical performance for lithium batteries

Aqueous-based LiFePO4 pastes to fabricate the cathode of lithium-ion battery were investigated with an emphasis on chemical control of suspension component interactions among LiFePO4 particulates, carbon black, carboxymethyl cellulose (CMC), and poly(acrylic acid) (PAA). The dispersion properties of LiFePO4 were characterized using electroacoustic, flow behavior and green microstructural observation. Correlation was made between the dispersion properties and electrochemical performance of the particles. It was found that the addition of PAA significantly decreases the viscosity of the LiFePO4 paste. The decrease of viscosity leads to increasing the solid concentration, which affects the electrochemical properties. The electrochemical characteristics of formulated pastes were evaluated using coin-type half cells. Although there is no significant difference between coin cells fabricated with CMC only and CMC/PAA combination in electrochemical cycling test, the dispersion properties of pastes indicate that the electrode fabricated with CMC/PAA, potentially, has much improved discharge capacity compared to that with CMC alone because of the possibility to increase active mass portion in electrode paste. (C) 2008 Elsevier B.V. All rights reserved.