Synthesis and Characterization of LiFePO 4 /Al/C Composite Cathode Material: Synthesis and Characterization of LiFePO 4 /Al/C Composite Cathode Material

LiFePO4/Al/C composite cathode materials were synthesized by two-step solid-state method. The crys- talline structure, morphology, the particle size and the coated state of the samples were characterized by XRD, SEM and TEM. The effect of the amounts of Al powder on the electrochemical properties of the composite was investi- gated. The results show that the interface reaction occurs between metal Al and LiFePO4, resulting in the formation of several by-products and the passive film on the surface of LiFePO4. The surface of LiFePO4 particles are coated by the irregularly shaped metal Al and a thin carbon layer of 1−2 nm. The LiFePO4/Al/C containing 3wt% Al shows the best electrochemical performances, with discharge specific capacity of 117.8 mAh/g at 25℃ and 10C rate, and discharge specific capacity of 105.6 mAh/g at −20℃ and 0.1C rate, and discharge capacity of samples at −20℃ is 73.8% of that of samples at 25℃.