Improvement of electrochemical performances of LiFePO4 cathode materials by coating of polythiophene

A series LiFePO4/polythiophene (LiFePO4/PTh) composites were synthesized by in situ polymerizing thiophene monomers on the surface of LiFePO4 particles. Electrochemical impedance spectra (EIS) measurements show that the coating of polythiophene significantly decreases the charge transfer resistance of LiFePO4 electrodes. Transmission electron microscopy (TEM) tests show that LiFePO4 could be completely coated by addition of proper amount of polythiophene. The electrochemical performance of polythiophene and LiFePO4/PTh for lithium insertion and extraction was examined by charge/discharge testing. The composites demonstrated an increased reversible capacity and better cycling ability compared to the bare LiFePO4.