L-Lysine-assisted solvothermal synthesis of hollow-like structure LiFePO4/C powders as cathode materials for Li-ion batteries

Abstract

LiFePO4/C powders were synthesized by solvothermal method using L-Lysine as a surfactant for controlling over the particle size and shape. The effects of L-Lysine contents on the phase, structure, microstructure, and electrochemical properties were studied by X-ray diffractometry, scanning electron microscopy, infrared spectroscopy, galvanic charge/discharge, and electrochemical impedance spectroscopy methods. As the amount of L-Lysine increased, the large sheet-like morphology was transformed to the spherical particulate and hollow-like structure. The LiFePO4/C powder obtained by 50 mmol L-Lysine showed the highest specific capacity of 96 mAh g−1 at 1C rate and high capacity retention of 95.6% following 650 cycles because of the low antisite defects and particulate morphology of LiFePO4. Moreover, the high rate capability of the LiFePO4/C powders was attributed to their small spherical particles and hollow-like structure, leading to the high electrochemical kinetics as investigated by electrochemical impedance spectroscopy.

Keywords

• LiFePO4
• Solvothermal synthesis
• L-Lysine
• Hollow-like structure
• Electrochemical properties