Modification of LiFePO4 with resorcinol-formaldehyde resin as carbon source

Lithium ion battery cathode material LiFePO4/C was prepared by using resorcinol-formaldehyde resin as carbon source. Effects of resin on purity and electrochemical performance of LiFePO4 were investigated by XRD and galvanostatic charge-discharge test. The results indicate that the hydrogen resulted from pyrolysis of resorcinol-formaldehyde resin can react with LiFeP04, then Fe2P, FeP and Li3PO4 are formed. Such impurities will lead the capacity of the materials decrease. The impurities can be reduced significantly by carbonization at lower temperature before calcination at higher temperature. The capacity and cycle property of LiFePO4 are improved greatly by the addition of resorcinol-formaldehyde resin. The specific discharge capacity of LiFePO4 reaches up to 160, 150, 135 and 120 mAh/g at 0.2C, 1C, 2C and 5C(1C=150 mA/g) rates, respectively.