Electrochemical Characteristics of Lithium Iron Phosphate with Multi-Walled Carbon Nanotube for Lithium Polymer Batteries

Abstract

In this study, we prepared phospho-olivine LiFePO4 nanoparticles as cathode materials for lithium polymer batteries by hydrothermal reaction at 150 degrees C. Multi-walled carbon nanotube (MWCNT) was added to enhance the electrical conductivity of LiFePO4. LiFePO4-MWCNT nanoparticles (0 wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt% and 10 wt%) were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). LiFePO4-MWCNT/SPE/Li cells were characterized electrochemically by charge/discharge experiments at a constant current density of 0.1 mA cm(-2) in a range between 2.5 and 4.3 V versus Li/Li+, cyclic voltammetry (CV) and ac impedance spectroscopy. The results showed that initial discharge capacity of LiFePO4 was 103 mA h g(-1). The discharge capacity of LiFePO4-MWCNT/SPE/Li cell with 7 wt% MWCNT was 129 mA h g(-1) at the first cycle and 130 mA h g(-1) after 30 cycles, respectively. It was demonstrated that cycling performance of LiFePO4-MWCNT/SPE/Li cell with 7 wt% MWCNT was better than that of LiFePO4/SPE/Li cell.