Abstract:
Element doping is one of the main ways to improve the charge/discharge performances of lithium iron phosphate (LiFePO
4) cathode materials. In this paper, modified LiFePO
4 was synthesized by a high-temperature solid-state reduction method using TiO
2 as a titanium source. The structural composition, micro-morphology, and physicochemical properties of titanium-doped LiFePO
4 were characterized by XRD, XPS, SEM, and BET, and further, the relationship between composition-structure and charge/discharge performances was carefully studied. The results indicate that the first discharge-specific capacity of titanium doped LiFePO
4 respectively reaches the maximum of 161.9 and 150.8 mAh/g at 0.1 C and 1 C rate, which is 4.72% and 7.48% higher than LiFePO
4 without titanium doping, and the capacity retention rate achieves as high as 98.54% after 150 cycles at 1 C rate. This is mainly attributed to the substitution of Fe
2+ by Ti
4+ into LiFePO
4 lattice, which stabilizes the crystal structure and inhibits the secondary growth of crystalline grains, leading to a decrease in Li
+ extraction/insertion paths and an increase in migration efficiency, thereby improving the discharge specific capacity, rate, and cycle performances of LiFePO
4.