Synthesis and Characterization of LiFePO₄-PANI Hybrid Material as Cathode for Lithium-Ion Batteries

This work focuses on the synthesis of LiFePO₄-PANI hybrid materials and studies their electrochemical properties (capacity, cyclability and rate capability) for use in lithium ion batteries. PANI synthesis and optimization was carried out by chemical oxidation (self-assembly process), using ammonium persulfate (APS) and H₃PO₄, obtaining a material with a high degree of crystallinity. For the synthesis of the LiFePO₄-PANI hybrid, a thermal treatment of LiFePO₄ particles was carried out in a furnace with polyaniline (PANI) and lithium acetate (AcOLi)-coated particles, using Ar/H₂ atmosphere. The pristine and synthetized powders were characterized by XRD, SEM, IR and TGA. The electrochemical characterizations were carried out by using CV, EIS and galvanostatic methods, obtaining a capacity of 95 mAhg^-1 for PANI, 120 mAhg^-1 for LiFePO₄ and 145 mAhg^-1 for LiFePO₄-PANI, at a charge/discharge rate of 0.1 C. At a charge/discharge rate of 2 C, the capacities were 70 mAhg^-1 for LiFePO₄ and 100 mAhg^-1 for LiFePO₄-PANI, showing that the PANI also had a favorable effect on the rate capability.