Abstract:
Polypyrrole was coated onto pure LiFePO
4 particles to form polypyrrole/lithium iron phosphate(PPy/LiFePO
4) composite material by chemical oxidative polymerization, with ferric trichloride(FeCl
3) as oxidant, benzene sulfonic acid sodium salt as dopant. The molecular structure and morphology of PPy/LiFePO
4 were characterized by FTIR, XRD and SEM. The electrochemical performances of composite were measured by electrochemical workstation and charge-discharge test system. It is found that the battery with PPy/LiFePO
4 composite as cathode shows better charge-discharge performance. The discharge capacity of PPy/LiFePO
4 composite is 163 mAh穏
-1, which is higher than that of LiFePO
4, when the mass fraction of PPy is 17.0% and the current is 0.1 mA.The discharge specific capacity of composite is still 94.9% of initial capacity after 50 cycles. Compared with pure LiFePO
4, the coating of proper amount of PPy can improve the electronic conductivity of LiFePO
4. As the effective utilization of LiFePO
4 increases, both the specific capacity and cycle performance of PPy/LiFePO
4 composite improves.