Hydrothermal synthesis of lithium iron phosphate using pyrrole as an efficient reducing agent

Abstract

Lithium iron phosphate (LiFePO4) is synthesized by a hydrothermal process using pyrrole as an efficient reducing agent and a subsequent calcination. Observations through a scanning electron microscope and a transmission electron microscope (TEM) show that LiFePO4 has a diameter and length of 500nm and 3μm, respectively. The results of TEM and X-ray diffraction confirm that the structure of LiFePO4 is orthorhombic olivine. Raman and X-ray photoelectron spectroscopy results indicate that Fe3+ oxidized from reactant Fe2+ by air reacts with pyrrole, generating polypyrrole (PPy), and reduces to Fe2+. PPy that is generated can also serve as a carbon source in the subsequent calcination. In addition, the electrochemical measurement results show that the energy capacity of calcined LiFePO4/PPy is 153mAhg−1 at 0.2C. Calcined LiFePO4/PPy offers promising cycle-life performance in lithium-ion batteries.