Effect of Cathode Slurry Composition on the Electrochemical Properties of Li-Ion Batteries

The performance difference between commercial and laboratory scale cells remains a problem to be solved. Different way of battery electrode preparation is considered to be the main reason underlying various battery performance. There are three main constituents of active material, conductive additives and binders found in a cathode. Active material acts as a Li⁺ source and conductive additives are used in order to enhance electronic conductivity. Binders are generally added to keep active material and conductive additives together and on the current collector. In this work, the effect of slurry compositions on electrochemical properties of Li-ion batteries is reported. Slurry preparation with various compositions of LiFePO₄ as an active material (76-88%), PVdF as a binder (6-12%) and Super P Carbon as a conductive additive (6-12%) has been studied. Charge-discharge curves and capacity fade of electrodes under varying C-rates are also investigated. Some of electrodes were pressed from selected samples in order to see the effect of pressing on the final performance. Results showed that varying PVdF and carbon content mainly effects charge-discharge characteristics. For unpressed samples, higher amount of PVdF and carbon could result higher maximum specific capacity and lower internal resistance during lithiation and delithiation of positive electrode. Pressing reduces the distance between slurry particles which enhances the conductivity of the prepared cell.